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NLM MeSH Drug Category Descriptions

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  • Abortifacient Agents

    Chemical substances that interrupt pregnancy after implantation.

    Abortifacient Agents, Nonsteroidal

    Non-steroidal chemical compounds with abortifacient activity.

    Abortifacient Agents, Steroidal

    Steroidal compounds with abortifacient activity.


    Substances that cause the adherence of two surfaces.  They include glues (properly collagen-derived adhesives), mucilages, sticky pastes, gums, resins, or latex.

    Adjuvants, Anesthesia

    Agents that are administered in association with anesthetics to increase effectiveness, improve delivery, or decrease required dosage.

    Adjuvants, Immunologic

    Substances that augment, stimulate, activate, potentiate, or modulate the immune response at either the cellular or humoral level.  The classical agents (Freund's adjuvant, BCG, Corynebacterium parvum, et al.) contain bacterial antigens.  Some are endogenous (e.g., histamine, interferon, transfer factor, tuftsin, interleukin-1).  Their mode of action is either non-specific, resulting in increased immune responsiveness to a wide variety of antigens, or antigen-specific, i.e., affecting a restricted type of immune response to a narrow group of antigens.  The therapeutic efficacy of many biological response modifiers is related to their antigen-specific immunoadjuvanticity.

    Adjuvants, Pharmaceutic

    Agents that aid or increase the action of the principle drug (DRUG SYNERGISM) or that affect the absorption, mechanism of action, metabolism, or excretion of the primary drug (PHARMACOKINETICS) in such a way as to enhance its effects.

    Adrenergic Agents

    Drugs that act on adrenergic receptors or affect the life cycle of adrenergic transmitters.  Included here are adrenergic agonists and antagonists and agents that affect the synthesis, storage, uptake, metabolism, or release of adrenergic transmitters.

    Adrenergic Agonists

    Drugs that bind to and activate adrenergic receptors.

    Adrenergic alpha-Agonists

    Drugs that selectively bind to and activate alpha adrenergic receptors.

    Adrenergic alpha-Antagonists

    Drugs that bind to but do not activate alpha-adrenergic receptors thereby blocking the actions of endogenous or exogenous adrenergic agonists.  Adrenergic alpha-antagonists are used in the treatment of hypertension, vasospasm, peripheral vascular disease, shock, and pheochromocytoma.

    Adrenergic Antagonists

    Drugs that bind to but do not activate ADRENERGIC RECEPTORS.  Adrenergic antagonists block the actions of the endogenous adrenergic transmitters EPINEPHRINE and NOREPINEPHRINE.

    Adrenergic beta-Agonists

    Drugs that selectively bind to and activate beta-adrenergic receptors.

    Adrenergic beta-Antagonists

    Drugs that bind to but do not activate beta-adrenergic receptors thereby blocking the actions of beta-adrenergic agonists.  Adrenergic beta-antagonists are used for treatment of hypertension, cardiac arrhythmias, angina pectoris, glaucoma, migraine headaches, and anxiety.

    Adrenergic Uptake Inhibitors

    Drugs that block the transport of adrenergic transmitters into axon terminals or into storage vesicles within terminals.  The tricyclic antidepressants (ANTIDEPRESSIVE AGENTS, TRICYCLIC) and amphetamines are among the therapeutically important drugs that may act via inhibition of adrenergic transport.  Many of these drugs also block transport of serotonin.

    Aerosol Propellants

    Compressed gases or vapors in a container which, upon release of pressure and expansion through a valve, carry another substance from the container.  They are used for cosmetics, household cleaners, and so on.  Examples are BUTANES; CARBON DIOXIDE; FLUOROCARBONS; NITROGEN; and PROPANE. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

    Affinity Labels

    Analogs of those substrates or compounds which bind naturally at the active sites of proteins, enzymes, antibodies, steroids, or physiological receptors.  These analogs form a stable covalent bond at the binding site, thereby acting as inhibitors of the proteins or steroids.


    Substances, usually of biological origin, that cause cells or other organic particles to aggregate and stick to each other.  They include those ANTIBODIES which cause aggregation or agglutination of particulate or insoluble ANTIGENS.

    Aggregation Inhibitors

    See Platelet Aggregation Inhibitors

    Air Pollutants

    Any substance in the air which could, if present in high enough concentration, harm humans, animals, vegetation or material.  Substances include GASES; PARTICULATE MATTER; and volatile ORGANIC CHEMICALS.

    Air Pollutants, Environmental

    See Air Pollutants

    Air Pollutants, Occupational

    Air pollutants found in the work area.  They are usually produced by the specific nature of the occupation.

    Air Pollutants, Radioactive

    Pollutants, present in air, which exhibit radioactivity.

    Alcohol Deterrents

    Substances interfering with the metabolism of ethyl alcohol, causing unpleasant side effects thought to discourage the drinking of alcoholic beverages.  Alcohol deterrents are used in the treatment of alcoholism.

    Aldosterone Antagonists

    Compounds which inhibit or antagonize the biosynthesis or actions of aldosterone.

    Alkylating Agents

    Highly reactive chemicals that introduce alkyl radicals into biologically active molecules and thereby prevent their proper functioning.  Many are used as antineoplastic agents, but most are very toxic, with carcinogenic, mutagenic, teratogenic, and immunosuppressant actions.  They have also been used as components in poison gases.


    Agents which are destructive to amebae, especially the parasitic species causing AMEBIASIS in man and animal.

    Anabolic Agents

    These compounds stimulate anabolism and inhibit catabolism.  They stimulate the development of muscle mass, strength, and power.


    Compounds capable of relieving pain without the loss of CONSCIOUSNESS.

    Analgesics, Non-Narcotic

    Drugs that have principally analgesic, antipyretic, and anti-inflammatory actions.  They do not bind to opioid receptors and are not classified under the Controlled Substances Act.  (From Drug Evaluations Annual, 1992, p109)

    Analgesics, Opioid

    Compounds with activity like OPIATE ALKALOIDS, acting at OPIOID RECEPTORS.  Properties include induction of ANALGESIA or NARCOSIS.

    Androgen Antagonists

    Compounds which inhibit or antagonize the biosynthesis or actions of androgens.


    Compounds that interact with ANDROGEN RECEPTORS in target tissues to bring about the effects similar to those of TESTOSTERONE.  Depending on the target tissues, androgenic effects can be on SEX DIFFERENTIATION; male reproductive organs, SPERMATOGENESIS; secondary male SEX CHARACTERISTICS; LIBIDO; development of muscle mass, strength, and power.


    Agents that are capable of inducing a total or partial loss of sensation, especially tactile sensation and pain.  They may act to induce general ANESTHESIA, in which an unconscious state is achieved, or may act locally to induce numbness or lack of sensation at a targeted site.

    Anesthetics, Combined

    The use of two or more chemicals simultaneously or sequentially to induce anesthesia.  The drugs need not be in the same dosage form.

    Anesthetics, Dissociative

    Intravenous anesthetics that induce a state of sedation, immobility, amnesia, and marked analgesia.  Subjects may experience a strong feeling of dissociation from the environment.  The condition produced is similar to NEUROLEPTANALGESIA, but is brought about by the administration of a single drug. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed)

    Anesthetics, General

    Agents that induce various degrees of analgesia; depression of consciousness, circulation, and respiration; relaxation of skeletal muscle; reduction of reflex activity; and amnesia.  There are two types of general anesthetics, inhalation and intravenous.  With either type, the arterial concentration of drug required to induce anesthesia varies with the condition of the patient, the desired depth of anesthesia, and the concomitant use of other drugs. (From AMA Drug Evaluations Annual, 1994, p.173)

    Anesthetics, Inhalation

    Gases or volatile liquids that vary in the rate at which they induce anesthesia; potency; the degree of circulation, respiratory, or neuromuscular depression they produce; and analgesic effects.  Inhalation anesthetics have advantages over intravenous agents in that the depth of anesthesia can be changed rapidly by altering the inhaled concentration.  Because of their rapid elimination, any postoperative respiratory depression is of relatively short duration. (From AMA Drug Evaluations Annual, 1994, p173)

    Anesthetics, Intravenous

    Ultrashort-acting anesthetics that are used for induction.  Loss of consciousness is rapid and induction is pleasant, but there is no muscle relaxation and reflexes frequently are not reduced adequately.  Repeated administration results in accumulation and prolongs the recovery time.  Since these agents have little if any analgesic activity, they are seldom used alone except in brief minor procedures. (From AMA Drug Evaluations Annual, 1994, p174)

    Anesthetics, Local

    Drugs that block nerve conduction when applied locally to nerve tissue in appropriate concentrations.  They act on any part of the nervous system and on every type of nerve fiber.  In contact with a nerve trunk, these anesthetics can cause both sensory and motor paralysis in the innervated area.  Their action is completely reversible. (From Gilman AG, et. al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed) Nearly all local anesthetics act by reducing the tendency of voltage-dependent sodium channels to activate.

    Angiogenesis Inducing Agents

    Agents that induce or stimulate the PHYSIOLOGIC ANGIOGENESIS process.  This is caused by a number of ANGIOGENIC PROTEINS.

    Angiogenesis Inhibitors

    Agents and endogenous substances that antagonize or inhibit the development of new blood vessels.

    Angiogenesis Modulating Agents

    Agents that modulate the PHYSIOLOGIC ANGIOGENESIS process.  This is accomplished by endogenous ANGIOGENIC PROTEINS and a variety of other chemicals and pharmaceutical agents.

    Angiotensin II Type 1 Receptor Blockers

    Agents that antagonize ANGIOTENSIN II TYPE 1 RECEPTOR.  Included are ANGIOTENSIN II analogs such as SARALASIN and biphenylimidazoles such as LOSARTAN.  Some are used as ANTIHYPERTENSIVE AGENTS.

    Angiotensin-Converting Enzyme Inhibitors

    A class of drugs whose main indications are the treatment of hypertension and heart failure.  They exert their hemodynamic effect mainly by inhibiting the renin-angiotensin system.  They also modulate sympathetic nervous system activity and increase prostaglandin synthesis.  They cause mainly vasodilation and mild natriuresis without affecting heart rate and contractility.

    Anion Exchange Resins

    High-molecular-weight insoluble polymers that contain functional cationic groups capable of undergoing exchange reactions with anions.


    Substances that counteract or neutralize acidity of the GASTROINTESTINAL TRACT.


    Agents destructive to parasitic worms.  They are used therapeutically in the treatment of HELMINTHIASIS in man and animal.

    Anti-Allergic Agents

    Agents that are used to treat allergic reactions.  Most of these drugs act by preventing the release of inflammatory mediators or inhibiting the actions of released mediators on their target cells. (From AMA Drug Evaluations Annual, 1994, p475)

    Anti-Anxiety Agents

    Agents that alleviate ANXIETY, tension, and ANXIETY DISORDERS, promote sedation, and have a calming effect without affecting clarity of consciousness or neurologic conditions.  Some are also effective as anticonvulsants, muscle relaxants, or anesthesia adjuvants.  ADRENERGIC BETA-ANTAGONISTS are commonly used in the symptomatic treatment of anxiety but are not included here.

    Anti-Anxiety Agents, Benzodiazepine

    A group of two-ring heterocyclic compounds consisting of a benzene ring fused to a diazepine ring.  Permitted is any degree of hydrogenation, any substituents and any H-isomer.  Anti-Anxiety Agents: Agents that alleviate ANXIETY, tension, and ANXIETY DISORDERS, promote sedation, and have a calming effect without affecting clarity of consciousness or neurologic conditions.  Some are also effective as anticonvulsants, muscle relaxants, or anesthesia adjuvants.  ADRENERGIC BETA-ANTAGONISTS are commonly used in the symptomatic treatment of anxiety but are not included here.

    Anti-Arrhythmia Agents

    Agents used for the treatment or prevention of cardiac arrhythmias.  They may affect the polarization-repolarization phase of the action potential, its excitability or refractoriness, or impulse conduction or membrane responsiveness within cardiac fibers.  Anti-arrhythmia agents are often classed into four main groups according to their mechanism of action: sodium channel blockade, beta-adrenergic blockade, repolarization prolongation, or calcium channel blockade.

    Anti-Asthmatic Agents

    Drugs that are used to treat asthma.

    Anti-Bacterial Agents

    Substances that reduce the growth or reproduction of BACTERIA.

    Anti-Dyskinesia Agents

    Drugs used in the treatment of movement disorders.  Most of these act centrally on dopaminergic or cholinergic systems.  Among the most important clinically are those used for the treatment of Parkinson disease (ANTIPARKINSON AGENTS) and those for the tardive dyskinesias.

    Anti-HIV Agents

    Agents used to treat AIDS and/or stop the spread of the HIV infection.  These do not include drugs used to treat symptoms or opportunistic infections associated with AIDS.

    Anti-Infective Agents

    Substances that prevent infectious agents or organisms from spreading or kill infectious agents in order to prevent the spread of infection.

    Anti-Infective Agents, Fluoroquinolone

    A group of QUINOLONES with at least one fluorine atom and a piperazinyl group

    Anti-Infective Agents, Local

    Substances used on humans and other animals that destroy harmful microorganisms or inhibit their activity.  They are distinguished from DISINFECTANTS, which are used on inanimate objects.

    Anti-Infective Agents, Quinolone

    A group of derivatives of naphthyridine carboxylic acid, quinoline carboxylic acid, or NALIDIXIC ACID.

    Anti-Infective Agents, Urinary

    Substances capable of killing agents causing urinary tract infections or of preventing them from spreading.

    Anti-Inflammatory Agents

    Substances that reduce or suppress INFLAMMATION.

    Anti-Inflammatory Agents, Non-Steroidal

    Anti-inflammatory agents that are not steroids.  In addition to anti-inflammatory actions, they have analgesic, antipyretic, and platelet-inhibitory actions.  They are used primarily in the treatment of chronic arthritic conditions and certain soft tissue disorders associated with pain and inflammation.  They act by blocking the synthesis of prostaglandins by inhibiting cyclooxygenase, which converts arachidonic acid to cyclic endoperoxides, precursors of prostaglandins.  Inhibition of prostaglandin synthesis accounts for their analgesic, antipyretic, and platelet-inhibitory actions; other mechanisms may contribute to their anti-inflammatory effects.  Certain NSAIDs also may inhibit lipoxygenase enzymes or TYPE C PHOSPHOLIPASES or may modulate T-cell function. (AMA Drug Evaluations Annual, 1994, p 1814-5)

    Anti-Obesity Agents

    Agents that increase energy expenditure and weight loss by neural and chemical regulation.  Beta-adrenergic agents and serotoninergic drugs have been experimentally used in patients with non-insulin dependent diabetes mellitus (NIDDM) to treat obesity.

    Anti-Retroviral Agents

    Agents used to treat RETROVIRIDAE INFECTIONS.

    Anti-Ulcer Agents

    Various agents with different action mechanisms used to treat or ameliorate PEPTIC ULCER or irritation of the gastrointestinal tract.  This has included ANTIBIOTICS to treat HELICOBACTER INFECTIONS; HISTAMINE H2 ANTAGONISTS to reduce GASTRIC ACID secretion; and ANTACIDS for symptomatic relief.


    See Anti-Bacterial Agents

    Antibiotics, Aminoglycoside

    Glycosylated compounds in which there is an amino substituent on the glycoside.  Some of them are clinically important ANTIBIOTICS.

    Antibiotics, Antifungal

    Antibiotics inhibiting the growth of or killing fungi and used in the treatment of various fungal diseases.

    Antibiotics, Antineoplastic

    Chemical substances, produced by microorganisms, inhibiting or preventing the proliferation of neoplasms.

    Antibiotics, Antitubercular

    Substances obtained from various species of microorganisms that are, alone or in combination with other agents, of use in treating various forms of tuberculosis; most of these agents are merely bacteriostatic, induce resistance in the organisms, and may be toxic.

    Antibiotics, Glycopeptide

    Proteins which contain carbohydrate groups attached covalently to the polypeptide chain.  The protein moiety is the predominant group with the carbohydrate making up only a small percentage of the total weight.

    Antibiotics, Lactam

    Cyclic AMIDES formed from aminocarboxylic acids by the elimination of water.  Lactims are the enol forms of lactams.

    Antibiotics, Macrolide

    A group of macrocyclic compounds formed by chain extension of multiple PROPIONATES and cyclized into a large (typically 12, 14, 16) membered lactone.  They are often glycosylated.  Many of them are ANTIBIOTICS.

    Antibiotics, Tetracycline

    A naphthacene antibiotic that inhibits AMINO ACYL TRNA binding during protein synthesis.

    Anticarcinogenic Agents

    Agents that reduce the frequency or rate of spontaneous or induced tumors independently of the mechanism involved.  They differ from antineoplastic agents in that they prevent neoplasms from forming.  The anticarcinogenic substances can be divided into three categories.  The first consists of compounds that prevent the formation of carcinogens from precursor substances.  The second group consists of "blocking agents" which inhibit carcinogenesis by preventing carcinogenic agents from reaching or reacting with critical target sites in the tissues.  The third group is the "suppressor agents" which act by suppression of expression of neoplasia in cells previously exposed to carcinogens that would otherwise cause neoplasms.

    Anticestodal Agents

    Agents used to treat tapeworm infestations in man or animals.

    Anticholesteremic Agents

    Substances used to lower plasma cholesterol levels.


    Agents that prevent blood clotting.  Naturally occurring agents in the blood are included only when they are used as drugs.


    Drugs used to prevent SEIZURES or reduce their severity.

    Antidepressive Agents

    Mood-stimulating drugs used primarily in the treatment of affective disorders and related conditions.  Several MONOAMINE OXIDASE INHIBITORS are useful as antidepressants apparently as a long-term consequence of their modulation of catecholamine levels.  The tricyclic compounds useful as antidepressive agents (ANTIDEPRESSIVE AGENTS, TRICYCLIC) also appear to act through brain catecholamine systems.  A third group (ANTIDEPRESSIVE AGENTS, SECOND-GENERATION) is a diverse group of drugs including some that act specifically on serotonergic systems.

    Antidepressive Agents, Second-Generation

    A structurally and mechanistically diverse group of drugs that are not tricyclics or monoamine oxidase inhibitors.  The most clinically important appear to act selectively on serotonergic systems, especially by inhibiting serotonin reuptake.

    Antidepressive Agents, Tricyclic

    Substances that contain a fused three-ring moiety and are used in the treatment of depression.  These drugs block the uptake of norepinephrine and serotonin into axon terminals and may block some subtypes of serotonin, adrenergic, and histamine receptors.  However the mechanism of their antidepressant effects is not clear because the therapeutic effects usually take weeks to develop and may reflect compensatory changes in the central nervous system.

    Antidiabetic Agents

    See Hypoglycemic Agents


    Miscellaneous agents found useful in the symptomatic treatment of diarrhea.  They have no effect on the agent(s) that cause diarrhea, but merely alleviate the condition.

    Antidiuretic Agents

    Agents that reduce the excretion of URINE, most notably the octapeptide VASOPRESSINS.


    Agents counteracting or neutralizing the action of POISONS.


    Drugs used to prevent NAUSEA or VOMITING.  Antiemetics act by a wide range of mechanisms.  Some act on the medullary control centers (the vomiting center and the chemoreceptive trigger zone) while others affect the peripheral receptors.

    Antifibrinolytic Agents

    Agents that prevent fibrinolysis or lysis of a blood clot or thrombus.  Several endogenous antiplasmins are known.  The drugs are used to control massive hemorrhage and in other coagulation disorders.

    Antifoaming Agents

    Agents used to prevent the formation of foam or to treat flatulence or bloat.

    Antifungal Agents

    Substances that destroy fungi by suppressing their ability to grow or reproduce.  They differ from FUNGICIDES, INDUSTRIAL because they defend against fungi present in human or animal tissues.

    Antihypertensive Agents

    Drugs used in the treatment of acute or chronic vascular HYPERTENSION regardless of pharmacological mechanism.  Among the antihypertensive agents are DIURETICS; (especially DIURETICS, THIAZIDE); ADRENERGIC BETA-ANTAGONISTS; ADRENERGIC ALPHA-ANTAGONISTS; ANGIOTENSIN-CONVERTING ENZYME INHIBITORS; CALCIUM CHANNEL BLOCKERS; GANGLIONIC BLOCKERS; and VASODILATOR AGENTS.

    Antilipemic Agents

    Substances used to treat HYPERLIPIDEMIAS.


    Agents used in the treatment of malaria.  They are usually classified on the basis of their action against plasmodia at different stages in their life cycle in the human. (From AMA, Drug Evaluations Annual, 1992, p1585)

    Antimanic Agents

    Agents that are used to treat bipolar disorders or mania associated with other affective disorders.


    Drugs that are chemically similar to naturally occurring metabolites, but differ enough to interfere with normal metabolic pathways. (From AMA Drug Evaluations Annual, 1994, p2033)

    Antimetabolites, Antineoplastic

    Antimetabolites that are useful in cancer chemotherapy.

    Antimitotic Agents

    Agents that arrest cells in MITOSIS, most notably TUBULIN MODULATORS.

    Antimutagenic Agents

    Agents that reduce the frequency or rate of spontaneous or induced mutations independently of the mechanism involved.

    Antinematodal Agents

    Substances used in the treatment or control of nematode infestations.  They are used also in veterinary practice.

    Antineoplastic Agents

    Substances that inhibit or prevent the proliferation of NEOPLASMS.

    Antineoplastic Agents, Alkylating

    A class of drugs that differs from other alkylating agents used clinically in that they are monofunctional and thus unable to cross-link cellular macromolecules.  Among their common properties are a requirement for metabolic activation to intermediates with antitumor efficacy and the presence in their chemical structures of N-methyl groups, that after metabolism, can covalently modify cellular DNA.  The precise mechanisms by which each of these drugs acts to kill tumor cells are not completely understood. (From AMA, Drug Evaluations Annual, 1994, p2026)

    Antineoplastic Agents, Combined

    The use of two or more chemicals simultaneously or sequentially in the drug therapy of neoplasms.  The drugs need not be in the same dosage form.

    Antineoplastic Agents, Hormonal

    Antineoplastic agents that are used to treat hormone-sensitive tumors.  Hormone-sensitive tumors may be hormone-dependent, hormone-responsive, or both.  A hormone-dependent tumor regresses on removal of the hormonal stimulus, by surgery or pharmacological block.  Hormone-responsive tumors may regress when pharmacologic amounts of hormones are administered regardless of whether previous signs of hormone sensitivity were observed.  The major hormone-responsive cancers include carcinomas of the breast, prostate, and endometrium; lymphomas; and certain leukemias. (From AMA Drug Evaluations Annual 1994, p2079)

    Antineoplastic Agents, Phytogenic

    Agents obtained from higher plants that have demonstrable cytostatic or antineoplastic activity.


    Naturally occurring or synthetic substances that inhibit or retard the oxidation of a substance to which it is added.  They counteract the harmful and damaging effects of oxidation in animal tissues.

    Antiparasitic Agents

    Drugs used to treat or prevent parasitic infections.

    Antiparkinson Agents

    Agents used in the treatment of Parkinson's disease.  The most commonly used drugs act on the dopaminergic system in the striatum and basal ganglia or are centrally acting muscarinic antagonists.


    Agents that are put on the SKIN to reduce SWEATING or prevent excess sweating (HYPERHIDROSIS).

    Antiplatyhelmintic Agents

    Agents used to treat cestode, trematode, or other flatworm infestations in man or animals.

    Antiprotozoal Agents

    Substances that are destructive to protozoans.


    Agents, usually topical, that relieve itching (pruritus).

    Antipsychotic Agents

    Agents that control agitated psychotic behavior, alleviate acute psychotic states, reduce psychotic symptoms, and exert a quieting effect.  They are used in schizophrenia, senile dementia, transient psychosis following surgery or myocardial infarction, etc.  These drugs are often referred to as neuroleptics alluding to the tendency to produce neurological side effects, but not all antipsychotics are likely to produce such effects.  Many of these drugs may also be effective against nausea, emesis, and pruritus.

    Antipsychotic Agents, Butyrophenone

    Compounds containing phenyl-1-butanone.  Antipsychotic Agents: Agents that control agitated psychotic behavior, alleviate acute psychotic states, reduce psychotic symptoms, and exert a quieting effect.  They are used in schizophrenia, senile dementia, transient psychosis following surgery or myocardial infarction, etc.  These drugs are often referred to as neuroleptics alluding to the tendency to produce neurological side effects, but not all antipsychotics are likely to produce such effects.  Many of these drugs may also be effective against nausea, emesis, and pruritus.

    Antipsychotic Agents, Phenothiazine

    Compounds containing dibenzo-1,4-thiazine.  Some of them are neuroactive.  Antipsychotic Agents: Agents that control agitated psychotic behavior, alleviate acute psychotic states, reduce psychotic symptoms, and exert a quieting effect.  They are used in schizophrenia, senile dementia, transient psychosis following surgery or myocardial infarction, etc.  These drugs are often referred to as neuroleptics alluding to the tendency to produce neurological side effects, but not all antipsychotics are likely to produce such effects.  Many of these drugs may also be effective against nausea, emesis, and pruritus.

    Antirheumatic Agents

    Drugs that are used to treat RHEUMATOID ARTHRITIS.

    Antirheumatic Agents, Gold

    A yellow metallic element with the atomic symbol Au, atomic number 79, and atomic weight 197.  It is used in jewelry, goldplating of other metals, as currency, and in dental restoration.  Many of its clinical applications, such as ANTIRHEUMATIC AGENTS, are in the form of its salts.  Antirheumatic Agents: Drugs that are used to treat RHEUMATOID ARTHRITIS.

    Antisense Elements (Genetics)

    Nucleic acids which hybridize to complementary sequences in other target nucleic acids causing the function of the latter to be affected.

    Antisickling Agents

    Agents used to prevent or reverse the pathological events leading to sickling of erythrocytes in sickle cell conditions.

    Antispermatogenic Agents

    Agents, either mechanical or chemical, which destroy spermatozoa in the male genitalia and block spermatogenesis.


    An endogenous family of proteins belonging to the serpin superfamily that neutralizes the action of thrombin.  Six naturally occurring antithrombins have been identified and are designated by Roman numerals I to VI. Of these, Antithrombin I (see FIBRIN) and ANTITHROMBIN III appear to be of major importance.

    Antithyroid Agents

    Agents that are used to treat hyperthyroidism by reducing the excessive production of thyroid hormones.

    Antitreponemal Agents

    Agents used to treat infections with bacteria of the genus TREPONEMA.  This includes SYPHILIS & YAWS.

    Antitrichomonal Agents

    Agents used to treat trichomonas infections.

    Antitubercular Agents

    Drugs used in the treatment of tuberculosis.  They are divided into two main classes: "first-line" agents, those with the greatest efficacy and acceptable degrees of toxicity used successfully in the great majority of cases; and "second-line" drugs used in drug-resistant cases or those in which some other patient-related condition has compromised the effectiveness of primary therapy.

    Antitussive Agents

    Agents that suppress cough.  They act centrally on the medullary cough center.  EXPECTORANTS, also used in the treatment of cough, act locally.

    Antiviral Agents

    Agents used in the prophylaxis or therapy of VIRUS DISEASES.  Some of the ways they may act include preventing viral replication by inhibiting viral DNA polymerase; binding to specific cell-surface receptors and inhibiting viral penetration or uncoating; inhibiting viral protein synthesis; or blocking late stages of virus assembly.


    Chemical agents or odors that stimulate sexual desires. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

    Appetite Depressants

    Agents that are used to decrease appetite.

    Appetite Stimulants

    Agents that are used to stimulate appetite.  These drugs are frequently used to treat anorexia associated with cancer and AIDS.

    Aromatase Inhibitors

    Compounds that inhibit AROMATASE in order to reduce production of estrogenic steroid hormones.


    Agents, usually topical, that cause the contraction of tissues for the control of bleeding or secretions.

    Autonomic Agents

    Agents affecting the function of, or mimicking the actions of, the autonomic nervous system and thereby having an effect on such processes as respiration, circulation, digestion, body temperature regulation, certain endocrine gland secretions, etc.

    Biocompatible Materials

    Synthetic or natural materials, other than DRUGS, that are used to replace or repair any body TISSUES or bodily function.

    Biological Response Modifiers

    See Immunologic Factors

    Blood Substitutes

    Substances that can carry oxygen to and carbon dioxide away from the tissues when introduced into the blood stream.  They are used to replace hemoglobin in severe hemorrhage and also to perfuse isolated organs.  The best known are perfluorocarbon emulsions and various hemoglobin solutions.

    Bone Cements

    Adhesives used to fix prosthetic devices to bones and to cement bone to bone in difficult fractures.  Synthetic resins are commonly used as cements.  A mixture of monocalcium phosphate, monohydrate, alpha-tricalcium phosphate, and calcium carbonate with a sodium phosphate solution is also a useful bone paste.

    Bone Density Conservation Agents

    Agents that inhibit BONE RESORPTION and/or favor BONE MINERALIZATION and BONE REGENERATION.  They are used to heal BONE FRACTURES and to treat METABOLIC BONE DISEASES.

    Bronchoconstrictor Agents

    Agents causing the narrowing of the lumen of a bronchus or bronchiole.

    Bronchodilator Agents

    Agents that cause an increase in the expansion of a bronchus or bronchial tubes.


    A chemical system that functions to control the levels of specific ions in solution.  When the level of hydrogen ion in solution is controlled the system is called a pH buffer.

    Calcium Channels

    Voltage-dependent cell membrane glycoproteins selectively permeable to calcium ions.  They are categorized as L-, T-, N-, P-, Q-, and R-types based on the activation and inactivation kinetics, ion specificity, and sensitivity to drugs and toxins.  The L- and T-types are present throughout the cardiovascular and central nervous systems and the N-, P-, Q-, & R-types are located in neuronal tissue.

    Calcium Channel Agonists

    Agents that increase calcium influx into calcium channels of excitable tissues.  This causes vasoconstriction in vascular smooth muscle and/or cardiac muscle cells as well as stimulation of insulin release from pancreatic islets.  Therefore, tissue-selective calcium agonists have the potential to combat cardiac failure and endocrinological disorders.  They have been used primarily in experimental studies in cell and tissue culture.

    Calcium Channel Blockers

    A class of drugs that act by selective inhibition of calcium influx through cell membranes or on the release and binding of calcium in intracellular pools.  Since they are inducers of vascular and other smooth muscle relaxation, they are used in the drug therapy of hypertension and cerebrovascular spasms, as myocardial protective agents, and in the relaxation of uterine spasms.

    Carbonic Anhydrase Inhibitors

    A class of compounds that reduces the secretion of H+ ions by the proximal kidney tubule through inhibition of CARBONIC ANHYDRASES.


    Substances that increase the risk of NEOPLASMS in humans or animals.  Both genotoxic chemicals, which affect DNA directly, and nongenotoxic chemicals, which induce neoplasms by other mechanism, are included.

    Carcinogens, Environmental

    Carcinogenic substances that are found in the environment.

    Cardiotonic Agents

    Agents that have a strengthening effect on the heart or that can increase cardiac output.  They may be CARDIAC GLYCOSIDES; SYMPATHOMIMETICS; or other drugs.  They are used after MYOCARDIAL INFARCT; CARDIAC SURGICAL PROCEDURES; in SHOCK; or in congestive heart failure (HEART FAILURE).

    Cardiovascular Agents

    Agents that affect the rate or intensity of cardiac contraction, blood vessel diameter, or blood volume.

    Cariogenic Agents

    Substances that promote DENTAL CARIES.

    Cariostatic Agents

    Substances that inhibit or arrest DENTAL CARIES formation. (Boucher's Clinical Dental Terminology, 4th ed)


    Agents that are used to evacuate the bowels to eliminate ingested NOXAE or to prepare for COLONOSCOPY.


    Strong alkaline chemicals that destroy soft body tissues resulting in a deep, penetrating type of burn, in contrast to corrosives, that result in a more superficial type of damage via chemical means or inflammation.  Caustics are usually hydroxides of light metals.  SODIUM HYDROXIDE and potassium hydroxide are the most widely used caustic agents in industry.  Medically, they have been used externally to remove diseased or dead tissues and destroy warts and small tumors.  The accidental ingestion of products (household and industrial) containing caustic ingredients results in thousands of injuries per year.

    Central Nervous System Agents

    A class of drugs producing both physiological and psychological effects through a variety of mechanisms.  They can be divided into "specific" agents, e.g., affecting an identifiable molecular mechanism unique to target cells bearing receptors for that agent, and "nonspecific" agents, those producing effects on different target cells and acting by diverse molecular mechanisms.  Those with nonspecific mechanisms are generally further classed according to whether they produce behavioral depression or stimulation.  Those with specific mechanisms are classed by locus of action or specific therapeutic use. (From Gilman AG, et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p252)

    Central Nervous System Depressants

    A very loosely defined group of drugs that tend to reduce the activity of the central nervous system.  The major groups included here are ethyl alcohol, anesthetics, hypnotics and sedatives, narcotics, and tranquilizing agents (antipsychotics and antianxiety agents).

    Central Nervous System Stimulants

    A loosely defined group of drugs that tend to increase behavioral alertness, agitation, or excitation.  They work by a variety of mechanisms, but usually not by direct excitation of neurons.  The many drugs that have such actions as side effects to their main therapeutic use are not included here.


    Naturally occurring family of beta-lactam cephalosporin-type antibiotics having a 7-methoxy group and possessing marked resistance to the action of beta-lactamases from gram-positive and gram-negative organisms.


    A group of broad-spectrum antibiotics first isolated from the Mediterranean fungus ACREMONIUM.  They contain the beta-lactam moiety thia-azabicyclo-octenecarboxylic acid also called 7-aminocephalosporanic acid.

    Channel Blockers

    See Calcium Channel Blockers

    Chelating Agents

    Organic chemicals that form two or more coordination bonds with a central metal ion.  Heterocyclic rings are formed with the central metal atom as part of the ring.  Some biological systems form metal chelates, e.g., the iron-binding porphyrin group of hemoglobin and the magnesium-binding chlorophyll of plants. (From Hawley's Condensed Chemical Dictionary, 12th ed) They are used chemically to remove ions from solutions, medicinally against microorganisms, to treat metal poisoning, and in chemotherapy protocols.

    Chemical Warfare Agents

    Chemicals that are used to cause the disturbance, disease, or death of humans during war.


    Compounds that cause reproductive sterility in organisms.  They are sometimes used to control pest populations by sterilizing males within the population.

    Cholagogues and Choleretics

    Gastrointestinal agents that stimulate the flow of bile into the duodenum (cholagogues) or stimulate the production of bile by the liver (choleretic).

    Cholinergic Agents

    Any drug used for its actions on cholinergic systems.  Included here are agonists and antagonists, drugs that affect the life cycle of ACETYLCHOLINE, and drugs that affect the survival of cholinergic neurons.  The term cholinergic agents is sometimes still used in the narrower sense of MUSCARINIC AGONISTS, although most modern texts discourage that usage.

    Cholinergic Agonists

    Drugs that bind to and activate cholinergic receptors.

    Cholinergic Antagonists

    Drugs that bind to but do not activate CHOLINERGIC RECEPTORS, thereby blocking the actions of ACETYLCHOLINE or cholinergic agonists.

    Cholinesterase Inhibitors

    Drugs that inhibit cholinesterases.  The neurotransmitter ACETYLCHOLINE is rapidly hydrolyzed, and thereby inactivated, by cholinesterases.  When cholinesterases are inhibited, the action of endogenously released acetylcholine at cholinergic synapses is potentiated.  Cholinesterase inhibitors are widely used clinically for their potentiation of cholinergic inputs to the gastrointestinal tract and urinary bladder, the eye, and skeletal muscles; they are also used for their effects on the heart and the central nervous system.

    Cholinesterase Reactivators

    Drugs used to reverse the inactivation of cholinesterase caused by organophosphates or sulfonates.  They are an important component of therapy in agricultural, industrial, and military poisonings by organophosphates and sulfonates.

    Chromogenic Compounds

    Colorless, endogenous or exogenous pigment precursors that may be transformed by biological mechanisms into colored compounds; used in biochemical assays and in diagnosis as indicators, especially in the form of enzyme substrates.  Synonym: chromogens (not to be confused with pigment-synthesizing bacteria also called chromogens).


    Exogenous substances used to promote blood coagulation.  The endogenous BLOOD COAGULATION FACTORS are considered to be coagulants only when administered as drugs.


    Agents useful in the treatment or prevention of COCCIDIOSIS in man or animals.

    Coloring Agents

    Chemicals and substances that impart color including soluble dyes and insoluble pigments.  They are used in INKS; PAINTS; and as INDICATORS AND REAGENTS.

    Complement Inactivating Agents

    Compounds that negatively regulate the cascade process of COMPLEMENT ACTIVATION.  Uncontrolled complement activation and resulting cell lysis is potentially dangerous for the host.

    Complex Mixtures

    Mixtures of many components in inexact proportions, usually natural, such as PLANT EXTRACTS; VENOMS; and MANURE.  These are distinguished from DRUG COMBINATIONS which have only a few components in definite proportions.

    Contraceptive Agents

    Chemical substances that prevent or reduce the probability of CONCEPTION.

    Contraceptive Agents, Female

    Chemical substances or agents with contraceptive activity in females.  Use for female contraceptive agents in general or for which there is no specific heading.

    Contraceptive Agents, Male

    Chemical substances or agents with contraceptive activity in males.  Use for male contraceptive agents in general or for which there is no specific heading.

    Contraceptives, Oral

    Compounds, usually hormonal, taken orally in order to block ovulation and prevent the occurrence of pregnancy.  The hormones are generally estrogen or progesterone or both.

    Contraceptives, Oral, Combined

    Fixed drug combinations administered orally for contraceptive purposes.

    Contraceptives, Oral, Hormonal

    Oral contraceptives which owe their effectiveness to hormonal preparations.

    Contraceptives, Oral, Sequential

    Drugs administered orally and sequentially for contraceptive purposes.

    Contraceptives, Oral, Synthetic

    Oral contraceptives which owe their effectiveness to synthetic preparations.

    Contraceptives, Postcoital

    Contraceptive substances to be used after COITUS.  These agents include high doses of estrogenic drugs; progesterone-receptor blockers; ANTIMETABOLITES; ALKALOIDS, and PROSTAGLANDINS.

    Contraceptives, Postcoital, Hormonal

    Postcoital contraceptives which owe their effectiveness to hormonal preparations.

    Contraceptives, Postcoital, Synthetic

    Postcoital contraceptives which owe their effectiveness to synthetic preparations.

    Contrast Media

    Substances used to allow enhanced visualization of tissues.


    Substances that act in the brain stem or spinal cord to produce tonic or clonic convulsions, often by removing normal inhibitory tone.  They were formerly used to stimulate respiration or as antidotes to barbiturate overdose.  They are now most commonly used as experimental tools.


    Substances intended to be applied to the human body for cleansing, beautifying, promoting attractiveness, or altering the appearance without affecting the body's structure or functions.  Included in this definition are skin creams, lotions, perfumes, lipsticks, fingernail polishes, eye and facial makeup preparations, permanent waves, hair colors, toothpastes, and deodorants, as well as any material intended for use as a component of a cosmetic product. (U.S. Food & Drug Administration Center for Food Safety & Applied Nutrition Office of Cosmetics Fact Sheet (web page) Feb 1995)

    Cross-Linking Reagents

    Reagents with two reactive groups, usually at opposite ends of the molecule, that are capable of reacting with and thereby forming bridges between side chains of amino acids in proteins; the locations of naturally reactive areas within proteins can thereby be identified; may also be used for other macromolecules, like glycoproteins, nucleic acids, or other.

    Cryoprotective Agents

    Substances that provide protection against the harmful effects of freezing temperatures.

    Culture Media

    Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells.  The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media.  Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.

    Cyclooxygenase 2 Inhibitors

    A subclass of cyclooxygenase inhibitors with specificity for CYCLOOXYGENASE-2.

    Cyclooxygenase Inhibitors

    Compounds or agents that combine with cyclooxygenase (PROSTAGLANDIN-ENDOPEROXIDE SYNTHASES) and thereby prevent its substrate-enzyme combination with arachidonic acid and the formation of eicosanoids, prostaglandins, and thromboxanes.

    Cysteine Proteinase Inhibitors

    Exogenous and endogenous compounds which inhibit CYSTEINE ENDOPEPTIDASES.


    Substances that are toxic to cells; they may be involved in immunity or may be contained in venoms.  These are distinguished from CYTOSTATIC AGENTS in degree of effect.  Some of them are used as CYTOTOXIC ANTIBIOTICS.  The mechanism of action of many of these are as ALKYLATING AGENTS or MITOSIS MODULATORS.

    Defoliants, Chemical

    Herbicides that remove leaves from trees and growing plants.  They may be either organic or inorganic.  Several of the more persistent types have been used in military operations and many are toxic. (From Hawley's Condensed Chemical Dictionary, 11th ed)

    Delayed-Action Preparations

    Dosage forms of a drug that act over a period of time by controlled-release processes or technology.

    Dental Disinfectants

    Chemicals especially for use on instruments to destroy pathogenic organisms. (Boucher, Clinical Dental Terminology, 4th ed)

    Dental Impression Materials

    Substances used to create an impression, or negative reproduction, of the teeth and dental arches.  These materials include dental plasters and cements, metallic oxide pastes, silicone base materials, or elastomeric materials.

    Dental Materials

    Materials used in the production of dental bases, restorations, impressions, prostheses, etc.

    Dental Veneers

    The use of a layer of tooth-colored material, usually porcelain or acrylic resin, applied to the surface of natural teeth, crowns, or pontics by fusion, cementation, or mechanical retention.


    Any preparations used for cleansing teeth; they usually contain an abrasive, detergent, binder and flavoring agent and may exist in the form of liquid, paste or powder; may also contain medicaments and caries preventives.

    Dentin-Bonding Agents

    Cements that act through infiltration and polymerization within the dentinal matrix and are used for dental restoration.  They can be adhesive resins themselves, adhesion-promoting monomers, or polymerization initiators that act in concert with other agents to form a dentin-bonding system.


    Agents that remove, correct, repress, or mask undesirable ODORS.  In personal hygiene, deodorants often contain astringent preparations that reduce SWEATING, referred to as ANTIPERSPIRANTS. (From Grant & Hackh's Chemical Dictionary, 5th ed)

    Dermatologic Agents

    Drugs used to treat or prevent skin disorders or for the routine care of skin.


    Specific substances elaborated by plants, microorganisms or animals that cause damage to the skin; they may be proteins or other specific factors or substances; constituents of spider, jellyfish or other venoms cause dermonecrosis and certain bacteria synthesize dermolytic agents.


    Purifying or cleansing agents, usually salts of long-chain aliphatic bases or acids, that exert cleansing (oil-dissolving) and antimicrobial effects through a surface action that depends on possessing both hydrophilic and hydrophobic properties.

    Dialysis Solutions

    Solutions prepared for exchange across a semipermeable membrane of solutes below a molecular size determined by the cutoff threshold of the membrane material.

    Dipeptidyl-Peptidase IV Inhibitors

    Compounds that supress the degradation of INCRETINS by blocking the action of DIPEPTIDYL-PEPTIDASE IV.  This helps to correct the defective INSULIN and GLUCAGON secretion characteristic of TYPE 2 DIABETES MELLITUS by stimulating insulin secretion and suppressing glucagon release.


    Substances used on inanimate objects that destroy harmful microorganisms or inhibit their activity.  Disinfectants are classed as complete, destroying SPORES as well as vegetative forms of microorganisms, or incomplete, destroying only vegetative forms of the organisms.  They are distinguished from ANTISEPTICS, which are local anti-infective agents used on humans and other animals. (From Hawley's Condensed Chemical Dictionary, 11th ed)


    Agents that promote the excretion of urine through their effects on kidney function.

    Diuretics, Osmotic

    Compounds that increase urine volume by increasing the amount of osmotically active solute in the urine.  Osmotic diuretics also increase the osmolarity of plasma.

    Diuretics, Thiazide

    Sodium Chloride Symporter Inhibitors: Agents that inhibit SODIUM CHLORIDE SYMPORTERS.  They act as DIURETICS.  Excess use is associated with HYPOKALEMIA.

    Dopamine Agents

    Any drugs that are used for their effects on dopamine receptors, on the life cycle of dopamine, or on the survival of dopaminergic neurons.

    Dopamine Agonists

    Drugs that bind to and activate dopamine receptors.

    Dopamine Antagonists

    Drugs that bind to but do not activate DOPAMINE RECEPTORS, thereby blocking the actions of dopamine or exogenous agonists.  Many drugs used in the treatment of psychotic disorders (ANTIPSYCHOTIC AGENTS) are dopamine antagonists, although their therapeutic effects may be due to long-term adjustments of the brain rather than to the acute effects of blocking dopamine receptors.  Dopamine antagonists have been used for several other clinical purposes including as ANTIEMETICS, in the treatment of Tourette syndrome, and for hiccup.  Dopamine receptor blockade is associated with NEUROLEPTIC MALIGNANT SYNDROME.

    Dopamine Uptake Inhibitors

    Drugs that block the transport of DOPAMINE into axon terminals or into storage vesicles within terminals.  Most of the ADRENERGIC UPTAKE INHIBITORS also inhibit dopamine uptake.

    Drug Carriers

    Forms to which substances are incorporated to improve the delivery and the effectiveness of drugs.  Drug carriers are used in drug-delivery systems such as the controlled-release technology to prolong in vivo drug actions, decrease drug metabolism, and reduce drug toxicity.  Carriers are also used in designs to increase the effectiveness of drug delivery to the target sites of pharmacological actions.  Liposomes, albumin microspheres, soluble synthetic polymers, DNA complexes, protein-drug conjugates, and carrier erythrocytes among others have been employed as biodegradable drug carriers.


    See Coloring Agents


    Agents that cause vomiting.  They may act directly on the gastrointestinal tract, bringing about emesis through local irritant effects, or indirectly, through their effects on the chemoreceptor trigger zone in the postremal area near the medulla.


    Oleagenous substances used topically to soothe, soften or protect skin or mucous membranes.  They are used also as vehicles for other dermatologic agents.


    Endogenous compounds that bind to CANNABINOID RECEPTORS.  They are structurally different from the CANNABINOIDS which are primarily derived from plants.

    Endothelium-Dependent Relaxing Factors

    Paracrine substances produced by the VASCULAR ENDOTHELIUM with VASCULAR SMOOTH MUSCLE relaxation (VASODILATION) activities.  Several factors have been identified, including NITRIC OXIDE and PROSTACYCLIN.

    Environmental Pollutants

    Substances which pollute the environment.  Use for environmental pollutants in general or for which there is no specific heading.

    Enzyme Activators

    Compounds or factors that act on a specific enzyme to increase its activity.

    Enzyme Inhibitors

    Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.

    Enzyme Reactivators

    Compounds which restore enzymatic activity by removing an inhibitory group bound to the reactive site of the enzyme.

    Estradiol Antagonists

    Compounds which inhibit or antagonize the biosynthesis or action of estradiol.

    Estrogen Antagonists

    Compounds which inhibit or antagonize the action or biosynthesis of estrogenic compounds.

    Estrogen Receptor Modulators

    Substances that possess antiestrogenic actions but can also produce estrogenic effects as well.  They act as complete or partial agonist or as antagonist.  They can be either steroidal or nonsteroidal in structure.


    Compounds that interact with ESTROGEN RECEPTORS in target tissues to bring about the effects similar to those of ESTRADIOL.  Estrogens stimulate the female reproductive organs, and the development of secondary female SEX CHARACTERISTICS.  Estrogenic chemicals include natural, synthetic, steroidal, or non-steroidal compounds.

    Estrogens, Non-Steroidal

    Non-steroidal compounds with estrogenic activity.

    Estrogens, Synthetic

    Steroidal compounds related to ESTRADIOL, the major mammalian female sex hormone.  Estradiol congeners include important estradiol precursors in the biosynthetic pathways, metabolites, derivatives, and synthetic steroids with estrogenic activities.


    Usually inert substances added to a prescription in order to provide suitable consistency to the dosage form.  These include binders, matrix, base or diluent in pills, tablets, creams, salves, etc.

    Excitatory Amino Acid Agents

    Drugs used for their actions on any aspect of excitatory amino acid neurotransmitter systems.  Included are drugs that act on excitatory amino acid receptors, affect the life cycle of excitatory amino acid transmitters, or affect the survival of neurons using excitatory amino acids.

    Excitatory Amino Acid Agonists

    Drugs that bind to and activate excitatory amino acid receptors.

    Excitatory Amino Acid Antagonists

    Drugs that bind to but do not activate excitatory amino acid receptors, thereby blocking the actions of agonists.


    Agents that increase mucous excretion.  Mucolytic agents, that is drugs that liquefy mucous secretions, are also included here.

    Explosive Agents

    Substances that are energetically unstable and can produce a sudden expansion of the material, called an explosion, which is accompanied by heat, pressure and noise.  Other things which have been described as explosive that are not included here are explosive action of laser heating, human performance, sudden epidemiological outbreaks, or fast cell growth.

    Fat Substitutes

    Compounds used in food or in food preparation to replace dietary fats.  They may be carbohydrate-, protein-, or fat-based.  Fat substitutes are usually lower in calories but provide the same texture as fats.

    Fatty Acid Synthesis Inhibitors

    Compounds that interfere with FATTY ACID SYNTHASE resulting in a reduction of FATTY ACIDS.  This is a target mechanism in humans of some ANTINEOPLASTIC AGENTS and ANTI-OBESITY AGENTS and of some ANTI-INFECTIVE AGENTS which interfere with CELL WALL and CELL MEMBRANE formation.

    Fertility Agents

    Drugs used to increase fertility or to treat infertility.

    Fertility Agents, Female

    Compounds which increase the capacity to conceive in females.

    Fertility Agents, Male

    Compounds which increase the capacity of the male to induce conception.


    Substances or mixtures that are added to the soil to supply nutrients or to make available nutrients already present in the soil, in order to increase plant growth and productivity.

    Fibrin Modulating Agents

    Agents that affect the function of FIBRIN in BLOOD COAGULATION.  They used as COAGULANTS for HEMORRHAGE or ANTICOAGULANTS for THROMBOSIS.

    Fibrinolytic Agents

    Fibrinolysin or agents that convert plasminogen to fibrinolysin (PLASMIN).


    Pharmacological agents destructive to nematodes in the superfamily Filarioidea.


    Agents employed in the preparation of histologic or pathologic specimens for the purpose of maintaining the existing form and structure of all of the constituent elements.  Great numbers of different agents are used; some are also decalcifying and hardening agents.  They must quickly kill and coagulate living tissue.

    Flavoring Agents

    Substances added to foods and medicine to improve the quality of taste.

    Fluorescent Dyes

    Agents that emit light after excitation by light.  The wave length of the emitted light is usually longer than that of the incident light.  Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.

    Fluorides, Topical

    Fluorides, usually in pastes or gels, used for topical application to reduce the incidence of DENTAL CARIES.

    Folic Acid Antagonists

    Inhibitors of the enzyme, dihydrofolate reductase (TETRAHYDROFOLATE DEHYDROGENASE), which converts dihydrofolate (FH2) to tetrahydrofolate (FH4).  They are frequently used in cancer chemotherapy. (From AMA, Drug Evaluations Annual, 1994, p2033)

    Food Additives

    Substances which are of little or no nutritive value, but are used in the processing or storage of foods or animal feed, especially in the developed countries; includes ANTIOXIDANTS; FOOD PRESERVATIVES; FOOD COLORING AGENTS; FLAVORING AGENTS; ANTI-INFECTIVE AGENTS (both plain and LOCAL); VEHICLES; EXCIPIENTS and other similarly used substances.  Many of the same substances are PHARMACEUTIC AIDS when added to pharmaceuticals rather than to foods.

    Food Coloring Agents

    Natural or synthetic dyes used as coloring agents in processed foods.

    Food Preservatives

    Substances capable of inhibiting, retarding or arresting the process of fermentation, acidification or other deterioration of foods.

    Free Radical Scavengers

    Substances that influence the course of a chemical reaction by ready combination with free radicals.  Among other effects, this combining activity protects pancreatic islets against damage by cytokines and prevents myocardial and pulmonary perfusion injuries.

    Fungicides, Industrial

    Chemicals that kill or inhibit the growth of fungi in agricultural applications, on wood, plastics, or other materials, in swimming pools, etc.

    GABA Agents

    Substances used for their pharmacological actions on GABAergic systems.  GABAergic agents include agonists, antagonists, degradation or uptake inhibitors, depleters, precursors, and modulators of receptor function.

    GABA Agonists

    Drugs that bind to and activate GAMMA-AMINOBUTYRIC ACID receptors (RECEPTORS, GABA).

    GABA Antagonists

    Drugs that bind to but do not activate GAMMA-AMINOBUTYRIC ACID receptors, thereby blocking the actions of endogenous GAMMA-AMINOBUTYRIC ACID or GAMMA-AMINOBUTYRIC ACID agonists.

    GABA Modulators

    Substances that do not act as agonists or antagonists but do affect the GAMMA-AMINOBUTYRIC ACID receptor-ionophore complex.  GABA-A receptors (RECEPTORS, GABA-A) appear to have at least three allosteric sites at which modulators act: a site at which BENZODIAZEPINES act by increasing the opening frequency of GAMMA-AMINOBUTYRIC ACID-activated chloride channels; a site at which BARBITURATES act to prolong the duration of channel opening; and a site at which some steroids may act.  GENERAL ANESTHETICS probably act at least partly by potentiating GABAergic responses, but they are not included here.

    Ganglionic Blockers

    Agents having as their major action the interruption of neural transmission at nicotinic receptors on postganglionic autonomic neurons.  Because their actions are so broad, including blocking of sympathetic and parasympathetic systems, their therapeutic use has been largely supplanted by more specific drugs.  They may still be used in the control of blood pressure in patients with acute dissecting aortic aneurysm and for the induction of hypotension in surgery.

    Ganglionic Stimulants

    Agents that mimic neural transmission by stimulation of the nicotinic receptors on postganglionic autonomic neurons.  Drugs that indirectly augment ganglionic transmission by increasing the release or slowing the breakdown of acetylcholine or by non-nicotinic effects on postganglionic neurons are not included here nor are the nonspecific cholinergic agonists.

    Gastrointestinal Agents

    Drugs used for their effects on the gastrointestinal system, as to control gastric acidity, regulate gastrointestinal motility and water flow, and improve digestion.


    A complex of three different closely related aminoglycoside sulfates, Gentamicins C1, C2, and C1(subA), obtained from Micromonospora purpurea and related species.  They are broad-spectrum antibiotics, but may cause ear and kidney damage.  They act to inhibit protein synthesis (GENETIC TRANSLATION).


    A group of CORTICOSTEROIDS that affect carbohydrate metabolism (GLUCONEOGENESIS, liver glycogen deposition, elevation of BLOOD SUGAR), inhibit ADRENOCORTICOTROPIC HORMONE secretion, and possess pronounced anti-inflammatory activity.  They also play a role in fat and protein metabolism, maintenance of arterial blood pressure, alteration of the connective tissue response to injury, reduction in the number of circulating lymphocytes, and functioning of the central nervous system.

    Glycine Agents

    Substances used for their pharmacological actions on glycinergic systems.  Glycinergic agents include agonists, antagonists, degradation or uptake inhibitors, depleters, precursors, and modulators of receptor function.

    Gout Suppressants

    Agents that increase uric acid excretion by the kidney (URICOSURIC AGENTS), decrease uric acid production (antihyperuricemics), or alleviate the pain and inflammation of acute attacks of gout.

    Growth Inhibitors

    Endogenous or exogenous substances which inhibit the normal growth of human and animal cells or micro-organisms, as distinguished from those affecting plant growth (= PLANT GROWTH REGULATORS).

    Growth Substances

    Signal molecules that are involved in the control of cell growth and differentiation.

    GTP Phosphohydrolase Activators

    Agents and factors that activate GTP phosphohydrolase activity.


    Drugs capable of inducing illusions, hallucinations, delusions, paranoid ideations, and other alterations of mood and thinking.  Despite the name, the feature that distinguishes these agents from other classes of drugs is their capacity to induce states of altered perception, thought, and feeling that are not experienced otherwise.

    Hazardous Substances

    Substances which, upon release into the atmosphere, water, or soil, or which, in direct contact with the skin, eyes, or mucous membranes, or as additives to food, cause health risks to humans or animals through absorption, inhalation, or ingestion.  The concept includes safe handling, transportation, and storage of these substances.


    Agents that cause agglutination of red blood cells.  They include antibodies, blood group antigens, lectins, autoimmune factors, bacterial, viral, or parasitic blood agglutinins, etc.


    Agents which improve the quality of the blood, increasing the hemoglobin level and the number of erythrocytes.  They are used in the treatment of anemias.

    Hematologic Agents

    Drugs that act on blood and blood-forming organs and those that affect the hemostatic system.

    Hemolytic Agents

    Substances that are toxic to blood in general, including the clotting mechanism; hematotoxins may refer to the hematopoietic system.


    Agents acting to arrest the flow of blood.  Absorbable hemostatics arrest bleeding either by the formation of an artificial clot or by providing a mechanical matrix that facilitates clotting when applied directly to the bleeding surface.  These agents function more at the capillary level and are not effective at stemming arterial or venous bleeding under any significant intravascular pressure.

    Heparin Antagonists

    Coagulant substances inhibiting the anticoagulant action of heparin.


    Pesticides used to destroy unwanted vegetation, especially various types of weeds, grasses (POACEAE), and woody plants.  Some plants develop HERBICIDE RESISTANCE.

    Herbicides, Triazine

    Heterocyclic rings containing three nitrogen atoms, commonly in 1,2,4 or 1,3,5 or 2,4,6 formats.  Some are used as HERBICIDES.

    Histamine Agents

    Drugs used for their actions on histaminergic systems.  Included are drugs that act at histamine receptors, affect the life cycle of histamine, or affect the state of histaminergic cells.

    Histamine Agonists

    Drugs that bind to and activate histamine receptors.  Although they have been suggested for a variety of clinical applications histamine agonists have so far been more widely used in research than therapeutically.

    Histamine Antagonists

    Drugs that bind to but do not activate histamine receptors, thereby blocking the actions of histamine or histamine agonists.  Classical antihistaminics block the histamine H1 receptors only.

    Histamine H1 Antagonists

    Drugs that selectively bind to but do not activate histamine H1 receptors, thereby blocking the actions of endogenous histamine.  Included here are the classical antihistaminics that antagonize or prevent the action of histamine mainly in immediate hypersensitivity.  They act in the bronchi, capillaries, and some other smooth muscles, and are used to prevent or allay motion sickness, seasonal rhinitis, and allergic dermatitis and to induce somnolence.  The effects of blocking central nervous system H1 receptors are not as well understood.

    Histamine H1 Antagonists, Non-Sedating

    A class of non-sedating drugs that bind to but do not activate histamine receptors (INVERSE AGONISM), thereby blocking the actions of histamine or histamine agonists.  These antihistamines represent a heterogenous group of compounds with differing chemical structures, adverse effects, distribution, and metabolism.  Compared to the early (first generation) antihistamines, these non-sedating antihistamines have greater receptor specificity, lower penetration of BLOOD-BRAIN BARRIER, and are less likely to cause drowsiness or psychomotor impairment.

    Histamine H2 Antagonists

    Drugs that selectively bind to but do not activate histamine H2 receptors, thereby blocking the actions of histamine.  Their clinically most important action is the inhibition of acid secretion in the treatment of gastrointestinal ulcers.  Smooth muscle may also be affected.  Some drugs in this class have strong effects in the central nervous system, but these actions are not well understood.

    Histamine H3 Antagonists

    Drugs that selectively bind to but do not activate HISTAMINE H3 RECEPTORS.  They have been used to correct SLEEP DISORDERS and MEMORY DISORDERS.

    HIV Fusion Inhibitors

    Inhibitors of the fusion of HIV to host cells, preventing viral entry.  This includes compounds that block attachment of HIV ENVELOPE PROTEIN GP120 to CD4 RECEPTORS.

    HIV Protease Inhibitors

    Inhibitors of HIV PROTEASE, an enzyme required for production of proteins needed for viral assembly.

    Hormone Antagonists

    Chemical substances which inhibit the function of the endocrine glands, the biosynthesis of their secreted hormones, or the action of hormones upon their specific sites.


    Chemical substances having a specific regulatory effect on the activity of a certain organ or organs.  The term was originally applied to substances secreted by various ENDOCRINE GLANDS and transported in the bloodstream to the target organs.  It is sometimes extended to include those substances that are not produced by the endocrine glands but that have similar effects.

    Hormones, Hormone Substitutes, and Hormone Antagonists

    A collective grouping for both naturally occurring and synthetic hormones, substitutes, and antagonists.

    Hydroxymethylglutaryl-CoA Reductase Inhibitors

    Compounds that inhibit HMG-CoA reductases.  They have been shown to directly lower cholesterol synthesis.

    Hypnotics and Sedatives

    Drugs used to induce drowsiness or sleep or to reduce psychological excitement or anxiety.

    Hypoglycemic Agents

    Agents which lower the blood glucose level.

    Immunologic Factors

    Biologically active substances whose activities affect or play a role in the functioning of the immune system.

    Immunosuppressive Agents

    Agents that suppress immune function by one of several mechanisms of action.  Classical cytotoxic immunosuppressants act by inhibiting DNA synthesis.  Others may act through activation of T-CELLS or by inhibiting the activation of HELPER CELLS.  While immunosuppression has been brought about in the past primarily to prevent rejection of transplanted organs, new applications involving mediation of the effects of INTERLEUKINS and other CYTOKINES are emerging.


    Semisynthetic conjugates of various toxic molecules, including RADIOACTIVE ISOTOPES and bacterial or plant TOXINS, with specific immune substances such as IMMUNOGLOBULINS; MONOCLONAL ANTIBODIES; and ANTIGENS.  The antitumor or antiviral immune substance carries the toxin to the tumor or infected cell where the toxin exerts its poisonous effect.


    Peptides which stimulate INSULIN release from the PANCREATIC BETA CELLS following oral nutrient ingestion, or postprandially.

    Indicators and Reagents

    Substances used for the detection, identification, analysis, etc. of chemical, biological, or pathologic processes or conditions.  Indicators are substances that change in physical appearance, e.g., color, at or approaching the endpoint of a chemical titration, e.g., on the passage between acidity and alkalinity.  Reagents are substances used for the detection or determination of another substance by chemical or microscopical means, especially analysis.  Types of reagents are precipitants, solvents, oxidizers, reducers, fluxes, and colorimetric reagents. (From Grant & Hackh's Chemical Dictionary, 5th ed, p301, p499)

    Inflammation Mediators

    The endogenous compounds that mediate inflammation (AUTACOIDS) and related exogenous compounds including the synthetic prostaglandins (PROSTAGLANDINS, SYNTHETIC).

    Insect Repellents

    Substances causing insects to turn away from them or reject them as food.


    Pesticides designed to control insects that are harmful to man.  The insects may be directly harmful, as those acting as disease vectors, or indirectly harmful, as destroyers of crops, food products, or textile fabrics.

    Insecticides, Carbamate

    Salts or esters of carbamic acid, H2NC(=O)OH, or of N-substituted carbamic acids: R2NC(=O)OR', (R' = hydrocarbyl or a cation).  The esters are often called URETHANE or urethan, a usage that is strictly correct only for the ethyl esters. (From IUPAC [Internet].  International Union Of Pure And Applied Chemistry; c1995 [updated 2004 Jan 9; cited 2004 May 3].  Available from  Insecticides: Pesticides designed to control insects that are harmful to man.  The insects may be directly harmful, as those acting as disease vectors, or indirectly harmful, as destroyers of crops, food products, or textile fabrics.

    Insecticides, Botanical

    See Insecticides

    Insecticides, Organophosphate

    See Cholinesterase Reactivators

    Insulin Antagonists

    Compounds which inhibit or antagonize the biosynthesis or action of insulin.

    Intercalating Agents

    Agents that are capable of inserting themselves between the successive bases in DNA, thus kinking, uncoiling or otherwise deforming it and therefore preventing its proper functioning.  They are used in the study of DNA.

    Interferon Inducers

    Agents that promote the production and release of interferons.  They include mitogens, lipopolysaccharides, and the synthetic polymers Poly A-U and Poly I-C.  Viruses, bacteria, and protozoa have been also known to induce interferons.


    Complexes of iodine and non-ionic SURFACE-ACTIVE AGENTS acting as carrier and solubilizing agent for the iodine in water.  Iodophors usually enhance bactericidal activity of iodine, reduce vapor pressure and odor, minimize staining, and allow wide dilution with water. (From Merck Index, 11th ed)

    Ion Exchange Resins

    High molecular weight, insoluble polymers which contain functional groups that are capable of undergoing exchange reactions (ION EXCHANGE) with either cations or anions.


    Chemical agents that increase the permeability of biological or artificial lipid membranes to specific ions.  Most ionophores are relatively small organic molecules that act as mobile carriers within membranes or coalesce to form ion permeable channels across membranes.  Many are antibiotics, and many act as uncoupling agents by short-circuiting the proton gradient across mitochondrial membranes.

    Iron Chelating Agents

    Organic chemicals that form two or more coordination links with an iron ion.  Once coordination has occurred, the complex formed is called a chelate.  The iron-binding porphyrin group of hemoglobin is an example of a metal chelate found in biological systems.


    Drugs that act locally on cutaneous or mucosal surfaces to produce inflammation; those that cause redness due to hyperemia are rubefacients; those that raise blisters are vesicants and those that penetrate sebaceous glands and cause abscesses are pustulants; tear gases and mustard gases are also irritants.

    Keratolytic Agents

    Agents that soften, separate, and cause desquamation of the cornified epithelium or horny layer of skin.  They are used to expose mycelia of infecting fungi or to treat corns, warts, and certain other skin diseases.

    Leprostatic Agents

    Substances that suppress Mycobacterium leprae, ameliorate the clinical manifestations of leprosy, and/or reduce the incidence and severity of leprous reactions.

    Leukotriene Antagonists

    A class of drugs designed to prevent leukotriene synthesis or activity by blocking binding at the receptor level.


    A molecule that binds to another molecule, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme.  Ligands are also molecules that donate or accept a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complex. (From Dorland, 27th ed)

    Lipotropic Agents

    Endogenous factors or drugs that act on fat metabolism by hastening the removal of or decreasing the deposit of fat in the liver. (From Dorland, 28th ed, p951)

    Lipoxygenase Inhibitors

    Compounds or agents that combine with lipoxygenase and thereby prevent its substrate-enzyme combination with arachidonic acid and the formation of the eicosanoid products hydroxyeicosatetraenoic acid and various leukotrienes.

    Luminescent Agents

    Compound such as LUMINESCENT PROTEINS that cause or emit light (PHYSICAL LUMINESCENCE).

    Luteolytic Agents

    Chemical compounds causing LUTEOLYSIS or degeneration.

    Membrane Transport Modulators


    Menstruation-Inducing Agents

    Chemical compounds that induce menstruation either through direct action on the reproductive organs or through indirect action by relieving another condition of which amenorrhea is a secondary result. (From Dorland, 27th ed)


    Essential dietary elements or organic compounds that are required in only small quantities for normal physiologic processes to occur.


    A group of CORTICOSTEROIDS primarily associated with the water and electrolyte balance.  This is accomplished through the effect on ION TRANSPORT in renal tubules, resulting in retention of sodium and loss of potassium.  Mineralocorticoid secretion is itself regulated by PLASMA VOLUME, serum potassium, and ANGIOTENSIN II.


    Agents causing contraction of the pupil of the eye.  Because the size of the pupil is under the antagonistic control of the sympathetic and parasympathetic systems, drugs affecting either system can cause miosis.  Drugs that mimic or potentiate the parasympathetic input to the circular constrictor muscle and drugs that inhibit sympathetic input to the radial dilator muscle tend to contract the pupils.  Some sources use the term miotics only for the parasympathomimetics but any drug used to induce miosis is included here.


    Substances that stimulate mitosis and lymphocyte transformation.  They include not only substances associated with LECTINS, but also substances from streptococci (associated with streptolysin S) and from strains of alpha-toxin-producing staphylococci. (Stedman, 25th ed)

    Mitosis Modulators

    Agents that affect MITOSIS of CELLS.

    Molecular Probes

    A group of atoms or molecules attached to other molecules or cellular structures and used in studying the properties of these molecules and structures.  Radioactive DNA or RNA sequences are used in MOLECULAR GENETICS to detect the presence of a complementary sequence by NUCLEIC ACID HYBRIDIZATION.


    Agents destructive to snails and other mollusks.

    Monoamine Oxidase Inhibitors

    A chemically heterogeneous group of drugs that have in common the ability to block oxidative deamination of naturally occurring monoamines. (From Gilman, et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p414)


    Monocyclic, bacterially produced or semisynthetic beta-lactam antibiotics.  They lack the double ring construction of the traditional beta-lactam antibiotics and can be easily synthesized.


    Solutions for rinsing the mouth, possessing cleansing, germicidal, or palliative properties. (From Boucher's Clinical Dental Terminology, 4th ed)

    Muscarinic Agonists

    Drugs that bind to and activate muscarinic cholinergic receptors (RECEPTORS, MUSCARINIC).  Muscarinic agonists are most commonly used when it is desirable to increase smooth muscle tone, especially in the GI tract, urinary bladder and the eye.  They may also be used to reduce heart rate.

    Muscarinic Antagonists

    Drugs that bind to but do not activate muscarinic cholinergic receptors (RECEPTORS, MUSCARINIC), thereby blocking the actions of endogenous acetylcholine or exogenous agonists.  Muscarinic antagonists have widespread effects including actions on the iris and ciliary muscle of the eye, the heart and blood vessels, secretions of the respiratory tract, GI system, and salivary glands, GI motility, urinary bladder tone, and the central nervous system.  Antagonists that discriminate among the various muscarinic receptor subtypes and might allow better control of peripheral and central actions are under development.

    Muscle Relaxants, Central

    A heterogeneous group of drugs used to produce muscle relaxation, excepting the neuromuscular blocking agents.  They have their primary clinical and therapeutic uses in the treatment of muscle spasm and immobility associated with strains, sprains, and injuries of the back and, to a lesser degree, injuries to the neck.  They have been used also for the treatment of a variety of clinical conditions that have in common only the presence of skeletal muscle hyperactivity, for example, the muscle spasms that can occur in MULTIPLE SCLEROSIS. (From Smith and Reynard, Textbook of Pharmacology, 1991, p358)


    Chemical agents that increase the rate of genetic mutation by interfering with the function of nucleic acids.  A clastogen is a specific mutagen that causes breaks in chromosomes.


    Toxic compounds produced by FUNGI.


    Agents that dilate the pupil.  They may be either sympathomimetics or parasympatholytics.  The latter cause cycloplegia or paralysis of accommodation at high doses and may precipitate glaucoma.  Mydriatics are used in eye diseases and to facilitate eye examination.

    Myeloablative Agonists

    Agents that destroy bone marrow activity.  They are used to prepare patients for BONE MARROW TRANSPLANTATION or STEM CELL TRANSPLANTATION.

    Narcotic Antagonists

    Agents inhibiting the effect of narcotics on the central nervous system.


    Agents that induce NARCOSIS.  This term is considered outdated due to imprecision but continues to be widely used.  Originally, agents that caused somnolence or induced sleep (STUPOR); now, any derivative, natural or synthetic, of OPIUM or MORPHINE or any substance that has their effects.  Narcotics are potent inducers of ANALGESIA and OPIOID-RELATED DISORDERS.

    Nasal Decongestants

    Drugs designed to treat inflammation of the nasal passages, generally the result of an infection (more often than not the common cold) or an allergy related condition, e.g., hay fever.  The inflammation involves swelling of the mucous membrane that lines the nasal passages and results in inordinate mucus production.  The primary class of nasal decongestants are vasoconstrictor agents. (From PharmAssist, The Family Guide to Health and Medicine, 1993)

    Natriuretic Agents

    Endogenous or exogenous chemicals that regulate the WATER-ELECTROLYTE BALANCE in the body.  They consist of peptides and non-peptide compounds.

    Nerve Growth Factors

    Factors which enhance the growth potentialities of sensory and sympathetic nerve cells.

    Neuromuscular Agents

    Drugs used for their actions on skeletal muscle.  Included are agents that act directly on skeletal muscle, those that alter neuromuscular transmission (NEUROMUSCULAR BLOCKING AGENTS), and drugs that act centrally as skeletal muscle relaxants (MUSCLE RELAXANTS, CENTRAL).  Drugs used in the treatment of movement disorders are ANTI-DYSKINESIA AGENTS.

    Neuromuscular Blocking Agents

    Drugs that interrupt transmission of nerve impulses at the skeletal neuromuscular junction.  They can be of two types, competitive, stabilizing blockers (NEUROMUSCULAR NONDEPOLARIZING AGENTS) or noncompetitive, depolarizing agents (NEUROMUSCULAR DEPOLARIZING AGENTS).  Both prevent acetylcholine from triggering the muscle contraction and they are used as anesthesia adjuvants, as relaxants during electroshock, in convulsive states, etc.

    Neuromuscular Depolarizing Agents

    Drugs that interrupt transmission at the skeletal neuromuscular junction by causing sustained depolarization of the motor end plate.  These agents are primarily used as adjuvants in surgical anesthesia to cause skeletal muscle relaxation.

    Neuromuscular Nondepolarizing Agents

    Drugs that interrupt transmission at the skeletal neuromuscular junction without causing depolarization of the motor end plate.  They prevent acetylcholine from triggering muscle contraction and are used as muscle relaxants during electroshock treatments, in convulsive states, and as anesthesia adjuvants.

    Neuroprotective Agents

    Drugs intended to prevent damage to the brain or spinal cord from ischemia, stroke, convulsions, or trauma.  Some must be administered before the event, but others may be effective for some time after.  They act by a variety of mechanisms, but often directly or indirectly minimize the damage produced by endogenous excitatory amino acids.


    Toxic substances from microorganisms, plants or animals that interfere with the functions of the nervous system.  Most venoms contain neurotoxic substances.  Myotoxins are included in this concept.


    See Neurotransmitter Agents

    Neurotransmitter Agents

    Substances used for their pharmacological actions on any aspect of neurotransmitter systems.  Neurotransmitter agents include agonists, antagonists, degradation inhibitors, uptake inhibitors, depleters, precursors, and modulators of receptor function.

    Neurotransmitter Uptake Inhibitors

    Drugs that inhibit the transport of neurotransmitters into axon terminals or into storage vesicles within terminals.  For many transmitters, uptake determines the time course of transmitter action so inhibiting uptake prolongs the activity of the transmitter.  Blocking uptake may also deplete available transmitter stores.  Many clinically important drugs are uptake inhibitors although the indirect reactions of the brain rather than the acute block of uptake itself is often responsible for the therapeutic effects.

    Nicotinic Agonists

    Drugs that bind to and activate nicotinic cholinergic receptors (RECEPTORS, NICOTINIC).  Nicotinic agonists act at postganglionic nicotinic receptors, at neuroeffector junctions in the peripheral nervous system, and at nicotinic receptors in the central nervous system.  Agents that function as neuromuscular depolarizing blocking agents are included here because they activate nicotinic receptors, although they are used clinically to block nicotinic transmission.

    Nicotinic Antagonists

    Drugs that bind to nicotinic cholinergic receptors (RECEPTORS, NICOTINIC) and block the actions of acetylcholine or cholinergic agonists.  Nicotinic antagonists block synaptic transmission at autonomic ganglia, the skeletal neuromuscular junction, and at central nervous system nicotinic synapses.

    Nitric Oxide Donors

    A diverse group of agents, with unique chemical structures and biochemical requirements, which generate NITRIC OXIDE.  These compounds have been used in the treatment of cardiovascular diseases and the management of acute myocardial infarction, acute and chronic congestive heart failure, and surgical control of blood pressure. (Adv Pharmacol 1995;34:361-81)

    Nootropic Agents

    Drugs used to specifically facilitate learning or memory, particularly to prevent the cognitive deficits associated with dementias.  These drugs act by a variety of mechanisms.  While no potent nootropic drugs have yet been accepted for general use, several are being actively investigated.


    Agents capable of exerting a harmful effect on the body.

    Nucleic Acid Synthesis Inhibitors

    Compounds that inhibit cell production of DNA or RNA.

    Oils, Volatile

    Oils which evaporate readily.  The volatile oils occur in aromatic plants, to which they give odor and other characteristics.  Most volatile oils consist of a mixture of two or more TERPENES or of a mixture of an eleoptene (the more volatile constituent of a volatile oil) with a stearopten (the more solid constituent).  The synonym essential oils refers to the essence of a plant, as its perfume or scent, and not to its indispensability.

    Ointment Bases

    Various mixtures of fats, waxes, animal and plant oils and solid and liquid hydrocarbons; vehicles for medicinal substances intended for external application; there are four classes: hydrocarbon base, absorption base, water-removable base and water-soluble base; several are also emollients.

    Oligodeoxyribonucleotides, Antisense

    Short fragments of DNA that are used to alter the function of target RNAs or DNAs to which they hybridize.

    Oligonucleotides, Antisense

    Short fragments of DNA or RNA that are used to alter the function of target RNAs or DNAs to which they hybridize.

    Ophthalmic Solutions

    Sterile solutions, essentially free from foreign particles and suitably compounded and dispensed, for instillation into the eye.  It does not include solutions for cleaning eyeglasses or CONTACT LENS SOLUTIONS. (From Dorland, 27th ed)


    Oxidizing agents or electron-accepting molecules in chemical reactions in which electrons are transferred from one molecule to another (OXIDATION-REDUCTION).  In vivo, it appears that phagocyte-generated oxidants function as tumor promoters or cocarcinogens rather than as complete carcinogens perhaps because of the high levels of endogenous antioxidant defenses.  It is also thought that oxidative damage in joints may trigger the autoimmune response that characterizes the persistence of the rheumatoid disease process.

    Oxidants, Photochemical

    Compounds that accept electrons in an oxidation-reduction reaction.  The reaction is induced by or accelerated by exposure to electromagnetic radiation in the spectrum of visible or ultraviolet light.


    Drugs that stimulate contraction of the myometrium.  They are used to induce LABOR, OBSTETRIC at term, to prevent or control postpartum or postabortion hemorrhage, and to assess fetal status in high risk pregnancies.  They may also be used alone or with other drugs to induce abortions (ABORTIFACIENTS).  Oxytocics used clinically include the neurohypophyseal hormone OXYTOCIN and certain prostaglandins and ergot alkaloids. (From AMA Drug Evaluations, 1994, p1157)


    Agents that inhibit the actions of the parasympathetic nervous system.  The major group of drugs used therapeutically for this purpose is the MUSCARINIC ANTAGONISTS.


    Drugs that mimic the effects of parasympathetic nervous system activity.  Included here are drugs that directly stimulate muscarinic receptors and drugs that potentiate cholinergic activity, usually by slowing the breakdown of acetylcholine (CHOLINESTERASE INHIBITORS).  Drugs that stimulate both sympathetic and parasympathetic postganglionic neurons (GANGLIONIC STIMULANTS) are not included here.


    A group of antibiotics that contain 6-aminopenicillanic acid with a side chain attached to the 6-amino group.  The penicillin nucleus is the chief structural requirement for biological activity.  The side-chain structure determines many of the antibacterial and pharmacological characteristics. (Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p1065)

    Peripheral Nervous System Agents

    Drugs that act principally at one or more sites within the peripheral neuroeffector systems, the autonomic system, and motor nerve-skeletal system. (From Smith and Reynard, Textbook of Pharmacology, 1991, p75)

    Peroxisome Proliferators

    A class of nongenotoxic CARCINOGENS that induce the production of hepatic PEROXISOMES and induce hepatic neoplasms after long-term administration.

    Pesticide Synergists

    Chemicals that, while not possessing inherent pesticidal activity, nonetheless promote or enhance the effectiveness of other pesticides when combined.


    Chemicals used to destroy pests of any sort.  The concept includes fungicides (FUNGICIDES, INDUSTRIAL); INSECTICIDES; RODENTICIDES; etc.

    Pharmaceutic Aids

    Substances which are of little or no therapeutic value, but are necessary in the manufacture, compounding, storage, etc., of pharmaceutical preparations or drug dosage forms.  They include SOLVENTS, diluting agents, and suspending agents, and emulsifying agents.  Also, ANTIOXIDANTS; PRESERVATIVES, PHARMACEUTICAL; COLORING AGENTS; FLAVORING AGENTS; VEHICLES; EXCIPIENTS; OINTMENT BASES.

    Pharmaceutical Solutions

    Homogeneous liquid preparations that contain one or more chemical substances dissolved, i.e., molecularly dispersed, in a suitable solvent or mixture of mutually miscible solvents.  For reasons of their ingredients, method of preparation, or use, they do not fall into another group of products.


    Chemical substances, excreted by an organism into the environment, that elicit behavioral or physiological responses from other organisms of the same species.  Perception of these chemical signals may be olfactory or by contact.

    Phosphodiesterase Inhibitors

    Compounds which inhibit or antagonize the biosynthesis or actions of phosphodiesterases.

    Photoaffinity Labels

    Biologically active molecules which are covalently bound to the enzymes or binding proteins normally acting on them.  Binding occurs due to activation of the label by ultraviolet light.  These labels are used primarily to identify binding sites on proteins.

    Photosensitizing Agents

    Drugs that are pharmacologically inactive but when exposed to ultraviolet radiation or sunlight are converted to their active metabolite to produce a beneficial reaction affecting the diseased tissue.  These compounds can be administered topically or systemically and have been used therapeutically to treat psoriasis and various types of neoplasms.


    PLANT EXTRACTS and compounds, primarily ISOFLAVONES, that mimic or modulate endogenous estrogens, usually by binding to ESTROGEN RECEPTORS.


    Chemicals functioning in the visual cycle in retinal rod cells.  Through excitation by visible light, a series of complex molecular changes occur that serve to trigger in the optical nerve endings an impulse transmitted to the brain, resulting in the perception of vision.  Pigments, Biological: Any normal or abnormal coloring matter in PLANTS; ANIMALS or micro-organisms.  Bile Pigments: Linear TETRAPYRROLES that give a characteristic color to BILE including: BILIRUBIN; BILIVERDIN; and bilicyanin.  Coloring Agents: Chemicals and substances that impart color including soluble dyes and insoluble pigments.  They are used in INKS; PAINTS; and as INDICATORS AND REAGENTS.

    Plant Growth Regulators

    Any of the hormones produced naturally in plants and active in controlling growth and other functions.  There are three primary classes: auxins, cytokinins, and gibberellins.

    Plasma Substitutes

    Any liquid used to replace blood plasma, usually a saline solution, often with serum albumins, dextrans or other preparations.  These substances do not enhance the oxygen- carrying capacity of blood, but merely replace the volume.  They are also used to treat dehydration.

    Plasminogen Activators

    A heterogeneous group of proteolytic enzymes that convert PLASMINOGEN to PLASMIN.  They are concentrated in the lysosomes of most cells and in the vascular endothelium, particularly in the vessels of the microcirculation.


    Materials incorporated mechanically in plastics (usually PVC) to increase flexibility, workability or distensibility; due to the non-chemical inclusion, plasticizers leach out from the plastic and are found in body fluids and the general environment.

    Platelet Aggregation Inhibitors

    Drugs or agents which antagonize or impair any mechanism leading to blood platelet aggregation, whether during the phases of activation and shape change or following the dense-granule release reaction and stimulation of the prostaglandin-thromboxane system.


    Substances which, when ingested, inhaled, or absorbed, or when applied to, injected into, or developed within the body in relatively small amounts may, by their chemical action, cause damage to structure or disturbance of function. (From Dorland, 27th ed)

    Potassium Channel Blockers

    A class of drugs that act by inhibition of potassium efflux through cell membranes.  Blockade of potassium channels prolongs the duration of ACTION POTENTIALS.  They are used as ANTI-ARRHYTHMIA AGENTS and VASODILATOR AGENTS.

    Preservatives, Pharmaceutical

    Substances added to pharmaceutical preparations to protect them from chemical change or microbial action.  They include ANTI-BACTERIAL AGENTS and antioxidants.


    A compound that, on administration, must undergo chemical conversion by metabolic processes before becoming the pharmacologically active drug for which it is a prodrug.

    Progestational Hormones, Synthetic

    Steroidal compounds related to PROGESTERONE, the major mammalian progestational hormone.  Progesterone congeners include important progesterone precursors in the biosynthetic pathways, metabolites, derivatives, and synthetic steroids with progestational activities.


    Compounds that interact with PROGESTERONE RECEPTORS in target tissues to bring about the effects similar to those of PROGESTERONE.  Primary actions of progestins, including natural and synthetic steroids, are on the UTERUS and the MAMMARY GLAND in preparation for and in maintenance of PREGNANCY.

    Prostaglandin Antagonists

    Compounds that inhibit the action of prostaglandins.

    Protease Inhibitors

    Compounds which inhibit or antagonize biosynthesis or actions of proteases (ENDOPEPTIDASES).

    Protective Agents

    Synthetic or natural substances which are given to prevent a disease or disorder or are used in the process of treating a disease or injury due to a poisonous agent.


    Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits.  The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.

    Protein Kinase Inhibitors

    Agents that inhibit PROTEIN KINASES.

    Protein Synthesis Inhibitors

    Compounds which inhibit the synthesis of proteins.  They are usually ANTI-BACTERIAL AGENTS or toxins.  Mechanism of the action of inhibition includes the interruption of peptide-chain elongation, the blocking the A site of ribosomes, the misreading of the genetic code or the prevention of the attachment of oligosaccharide side chains to glycoproteins.

    Psychotropic Drugs

    A loosely defined grouping of drugs that have effects on psychological function.  Here the psychotropic agents include the antidepressive agents, hallucinogens, and tranquilizing agents (including the antipsychotics and anti-anxiety agents).

    Pulmonary Surfactants

    Substances and drugs that lower the SURFACE TENSION of the mucoid layer lining the PULMONARY ALVEOLI.


    Substances capable of increasing BODY TEMPERATURE and cause FEVER and may be used for FEVER THERAPY.  They may be of microbial origin, often POLYSACCHARIDES, and may contaminate distilled water.

    Radiation-Protective Agents

    Drugs used to protect against ionizing radiation.  They are usually of interest for use in radiation therapy but have been considered for other, e.g. military, purposes.

    Radiation-Sensitizing Agents

    Drugs used to potentiate the effectiveness of radiation therapy in destroying unwanted cells.

    Radioactive Pollutants

    Radioactive substances which act as pollutants.  They include chemicals whose radiation is released via radioactive waste, nuclear accidents, fallout from nuclear explosions, and the like.


    Compounds that are used in medicine as sources of radiation for radiotherapy and for diagnostic purposes.  They have numerous uses in research and industry. (Martindale, The Extra Pharmacopoeia, 30th ed, p1161)

    Receptors, Androgen

    Proteins, generally found in the cytoplasm, that specifically bind androgens and mediate their cellular actions.  The complex of the androgen and receptor migrates to the nucleus where it induces transcription of specific segments of DNA.

    Reducing Agents

    Materials that add an electron to an element or compound, that is, decrease the positiveness of its valence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)

    Renal Agents

    Drugs used for their effects on the kidneys' regulation of body fluid composition and volume.  The most commonly used are the diuretics.  Also included are drugs used for their antidiuretic and uricosuric actions, for their effects on the kidneys' clearance of other drugs, and for diagnosis of renal function.

    Reproductive Control Agents

    Substances used either in the prevention or facilitation of pregnancy.

    Resins, Synthetic

    Polymers of high molecular weight which at some stage are capable of being molded and then harden to form useful components.

    Respiratory System Agents

    Drugs used for their effects on the respiratory system.

    Reverse Transcriptase Inhibitors

    Inhibitors of reverse transcriptase (RNA-DIRECTED DNA POLYMERASE), an enzyme that synthesizes DNA on an RNA template.

    Riot Control Agents, Chemical

    Chemical substances which are employed during a riot in order to control or disperse the rioting parties.


    Substances used to destroy or inhibit the action of rats, mice, or other rodents.

    Rosaniline Dyes

    Compounds that contain the triphenylmethane aniline structure found in rosaniline.  Many of them have a characteristic magenta color and are used as COLORING AGENTS.


    Agents that act systemically to kill adult schistosomes.

    Sclerosing Solutions

    Chemical agents injected into veins to cause localized THROMBOSIS and eventual fibrosis and obliteration of the vessels.  They are used in the treatment of VARICOSE VEINS, hemorrhoids, gastric and esophageal varices, and peptic ulcer hemorrhage.

    Sedatives, Barbiturate

    A class of chemicals derived from barbituric acid or thiobarbituric acid.  Many of these are GABA MODULATORS used as HYPNOTICS AND SEDATIVES, as ANESTHETICS, or as ANTICONVULSANTS.  Hypnotics and Sedatives: Drugs used to induce drowsiness or sleep or to reduce psychological excitement or anxiety.

    Selective Estrogen Receptor Modulators

    A structurally diverse group of compounds distinguished from ESTROGENS by their ability to bind and activate ESTROGEN RECEPTORS but act as either an agonist or antagonist depending on the tissue type and hormonal milieu.  They are classified as either first generation because they demonstrate estrogen agonist properties in the ENDOMETRIUM or second generation based on their patterns of tissue specificity. (Horm Res 1997;48:155-63)

    Sensory System Agents

    Drugs that act on neuronal sensory receptors resulting in an increase, decrease, or modification of afferent nerve activity. (From Smith and Reynard, Textbook of Pharmacology, 1991, p367)

    Serine Proteinase Inhibitors

    Exogenous or endogenous compounds which inhibit SERINE ENDOPEPTIDASES.

    Serotonin Agents

    Drugs used for their effects on serotonergic systems.  Among these are drugs that affect serotonin receptors, the life cycle of serotonin, and the survival of serotonergic neurons.

    Serotonin Agonists

    Agents that have an affinity for serotonin receptors and are able to mimic the effects of serotonin by stimulating the physiologic activity at the cell receptors.  These compounds are used as antidepressants, anxiolytics, and in the treatment of MIGRAINE DISORDERS.

    Serotonin Antagonists

    Drugs that bind to but do not activate serotonin receptors, thereby blocking the actions of serotonin or serotonin agonists.

    Serotonin Uptake Inhibitors

    Compounds that specifically inhibit the reuptake of serotonin in the brain.  This increases the serotonin concentration in the synaptic cleft which then activates serotonin receptors to a greater extent.  These agents have been used in treatment of depression, panic disorder, obsessive-compulsive behavior, and alcoholism, as analgesics, and to treat obesity and bulimia.  Many of the ADRENERGIC UPTAKE INHIBITORS also inhibit serotonin uptake; they are not included here.


    Low-molecular-weight compounds produced by microorganisms that aid in the transport and sequestration of ferric iron. (The Encyclopedia of Molecular Biology, 1994)

    Smoking Cessation

    Discontinuation of the habit of smoking, the inhaling and exhaling of tobacco smoke.

    Sodium Channel Blockers

    A class of drugs that act by inhibition of sodium influx through cell membranes.  Blockade of sodium channels slows the rate and amplitude of initial rapid depolarization, reduces cell excitability, and reduces conduction velocity.

    Sodium Chloride Symporter Inhibitors

    Agents that inhibit SODIUM CHLORIDE SYMPORTERS.  They act as DIURETICS.  Excess use is associated with HYPOKALEMIA.

    Sodium Potassium Chloride Symporter Inhibitors

    Agents that inhibit SODIUM-POTASSIUM-CHLORIDE SYMPORTERS which are concentrated in the thick ascending limb at the junction of the LOOP OF HENLE and KIDNEY TUBULES, DISTAL.  They act as DIURETICS.  Excess use is associated with HYPOKALEMIA and HYPERGLYCEMIA.

    Soil Pollutants

    Substances which pollute the soil.  Use for soil pollutants in general or for which there is no specific heading.


    Liquids that dissolve other substances (solutes), generally solids, without any change in chemical composition, as, water containing sugar. (Grant & Hackh's Chemical Dictionary, 5th ed)

    Spermatocidal Agents

    Chemical substances that are destructive to spermatozoa used as topically administered vaginal contraceptives.

    Sulfhydryl Reagents

    Chemical agents that react with SH groups.  This is a chemically diverse group that is used for a variety of purposes.  Among these are enzyme inhibition, enzyme reactivation or protection, and labelling.

    Sunscreening Agents

    Chemical or physical agents that protect the skin from sunburn and erythema by absorbing or blocking ultraviolet radiation.

    Surface-Active Agents

    Agents that modify interfacial tension of water; usually substances that have one lipophilic and one hydrophilic group in the molecule; includes soaps, detergents, emulsifiers, dispersing and wetting agents, and several groups of antiseptics.

    Surgical Fixation Devices

    Devices used to hold tissue structures together for repair, reconstruction or to close wounds.  They may consist of adsorbable or non-adsorbable, natural or synthetic materials.  They include tissue adhesives, skin tape, sutures, buttons, staples, clips, screws, etc., each designed to conform to various tissue geometries.

    Sweetening Agents

    Substances that sweeten food, beverages, medications, etc., such as sugar, saccharine or other low-calorie synthetic products. (From Random House Unabridged Dictionary, 2d ed)


    Drugs that inhibit the actions of the sympathetic nervous system by any mechanism.  The most common of these are the ADRENERGIC ANTAGONISTS and drugs that deplete norepinephrine or reduce the release of transmitters from adrenergic postganglionic terminals (see ADRENERGIC AGENTS).  Drugs that act in the central nervous system to reduce sympathetic activity (e.g., centrally acting alpha-2 adrenergic agonists, see ADRENERGIC ALPHA-AGONISTS) are included here.


    Drugs that mimic the effects of stimulating postganglionic adrenergic sympathetic nerves.  Included here are drugs that directly stimulate adrenergic receptors and drugs that act indirectly by provoking the release of adrenergic transmitters.

    Tear Gases

    Gases that irritate the eyes, throat, or skin.  Severe lacrimation develops upon irritation of the eyes.


    An agent that causes the production of physical defects in the developing embryo.


    Beta-lactam antibiotics that differ from PENICILLINS in having the thiazolidine sulfur atom replaced by carbon, the sulfur then becoming the first atom in the side chain.  They are unstable chemically, but have a very broad antibacterial spectrum.  Thienamycin and its more stable derivatives are proposed for use in combinations with enzyme inhibitors.

    Tissue Adhesives

    Substances used to cause adherence of tissue to tissue or tissue to non-tissue surfaces, as for prostheses.

    Tocolytic Agents

    Drugs that prevent preterm labor and immature birth by suppressing uterine contractions (TOCOLYSIS).  Agents used to delay premature uterine activity include magnesium sulfate, beta-mimetics, oxytocin antagonists, calcium channel inhibitors, and adrenergic beta-receptor agonists.  The use of intravenous alcohol as a tocolytic is now obsolete.


    A dentifrice in paste form; usually contains binder, humectant, an abrasive, a detergent, flavoring agent and often caries preventives, anti-infective agents or other medicaments.

    Trace Elements

    A group of chemical elements that are needed in minute quantities for the proper growth, development, and physiology of an organism. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

    Tranquilizing Agents

    A traditional grouping of drugs said to have a soothing or calming effect on mood, thought, or behavior.  Included here are the ANTI-ANXIETY AGENTS (minor tranquilizers), ANTIMANIC AGENTS, and the ANTIPSYCHOTIC AGENTS (major tranquilizers).  These drugs act by different mechanisms and are used for different therapeutic purposes.

    Trypanocidal Agents

    Agents destructive to the protozoal organisms belonging to the suborder TRYPANOSOMATINA.

    Trypsin Inhibitors

    Serine proteinase inhibitors which inhibit trypsin.  They may be endogenous or exogenous compounds.

    Tubulin Modulators

    Agents that interact with TUBULIN to inhibit or promote polymerization of MICROTUBULES.

    Uncoupling Agents

    Chemical agents that uncouple oxidation from phosphorylation in the metabolic cycle so that ATP synthesis does not occur.  Included here are those IONOPHORES that disrupt electron transfer by short-circuiting the proton gradient across mitochondrial membranes.

    Uricosuric Agents

    Gout suppressants that act directly on the renal tubule to increase the excretion of uric acid, thus reducing its concentrations in plasma.


    Suspensions of killed or attenuated microorganisms (bacteria, viruses, fungi, protozoa, or rickettsiae), antigenic proteins derived from them, or synthetic constructs, administered for the prevention, amelioration, or treatment of infectious and other diseases.

    Vasoconstrictor Agents

    Drugs used to cause constriction of the blood vessels.

    Vasodilator Agents

    Drugs used to cause dilation of the blood vessels.


    A carrier or inert medium used as a solvent (or diluent) in which the medicinally active agent is formulated and or administered. (Dictionary of Pharmacy, 1986)

    Vitamin B Complex

    A group of water-soluble vitamins, some of which are COENZYMES.


    Organic substances that are required in small amounts for maintenance and growth, but which cannot be manufactured by the human body.

    Water Pollutants, Chemical

    Chemical compounds which pollute the water of rivers, streams, lakes, the sea, reservoirs, or other bodies of water.

    Wetting Agents

    A surfactant that renders a surface wettable by water or enhances the spreading of water over the surface; used in foods and cosmetics; important in contrast media; also with contact lenses, dentures, and some prostheses.  Synonyms: humectants; hydrating agents.


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