drugs definition of drugs in the Free Online Encyclopedia.

drugs, substances used in medicine either externally or internally for curing, alleviating, or preventing a disease or deficiency. At the turn of the century only a few medically effective substances were widely used scientifically, among them ether ether, any of a number of organic compounds whose molecules contain two hydrocarbon groups joined by single bonds to an oxygen atom. The most common of these compounds is ethyl ether, CH₃CH₂OCH₂CH₃
..... Click the link for more information. , morphine morphine, principal derivative of opium , which is the juice in the unripe seed pods of the opium poppy , Papaver somniferum. It was first isolated from opium in 1803 by the German pharmacist F. W. A.
..... Click the link for more information. , digitalis digitalis (dĭj'ĭtăl`ĭs)
..... Click the link for more information. , diphtheria antitoxin, smallpox vaccine, iron iron, metallic chemical element; symbol Fe [Lat. ferrum]; at. no. 26; at. wt. 55.847; m.p. about 1,535°C;; b.p. about 2,750°C;; sp. gr. 7.87 at 20°C;; valence +2, +3, +4, or +6. Iron is biologically significant.
..... Click the link for more information. , quinine quinine (kwī`nīn', kwĭnēn`), white crystalline alkaloid with a bitter taste.
..... Click the link for more information. , iodine iodine (ī`ədīn, –dĭn) [Gr.,=violet], nonmetallic chemical element; symbol I; at. no. 53; at. wt. 126.9045; m.p. 113.
..... Click the link for more information. , alcohol, and mercury mercury or quicksilver [from the Roman god Mercury], metallic chemical element; symbol Hg [Lat. hydrargyrum=liquid silver]; at. no. 80; at. wt. 200.59; m.p. −38.842°C;; b.p. 356.58°C;; sp. gr. 13.
..... Click the link for more information. . Since then, and particularly since World War II, many important new drugs have been developed, making chemotherapy an important part of medical practice. Such drugs include the antibiotics antibiotic, any of a variety of substances, usually obtained from microorganisms, that inhibit the growth of or destroy certain other microorganisms.

Types of Antibiotics

..... Click the link for more information. , which act against bacteria and fungi; quinacrine and other synthetics that act against malaria and other parasitic infections; cardiovascular drugs, including beta-blockers beta-blocker or beta-adrenergic blocking agent (bā`tə ăd'rənûr`jĭk)
..... Click the link for more information. and ACE inhibitors Angiotensin-receptor blockers (ARBs), such as losartan (Cozaar) and valsartan (Diovan), reduce hypertension by displacing angiotensin 2 from receptors on the surface of cells. ARBs are used as alternatives to the less expensive ACE inhibitors because they have fewer side effects.
..... Click the link for more information. ; diuretics diuretic (dī'yərĕt`ĭk), drug used to increase urine formation and output.
..... Click the link for more information. , which increase the rate of urine flow; whole blood, plasma, and blood derivatives; anticoagulants anticoagulant (ăn'tēkōăg`yələnt)
..... Click the link for more information. such as heparin heparin (hĕp`ərĭn), anticoagulant produced by cells in many animals.
..... Click the link for more information. and coumarin; various smooth-muscle relaxants such as papaverine papaverine (pəpăv`ərēn), alkaloid found in opium that acts as a muscle relaxant and vasodilator.
..... Click the link for more information. , used in heart and vascular diseases; smooth-muscle stimulants; immunologic agents, which protect against many diseases and allergenic substances; hormones such as thyroxine thyroxine (thīrŏk`sēn), substance secreted by the thyroid gland .
..... Click the link for more information. , insulin insulin, hormone secreted by the β cells of the islets of Langerhans, specific groups of cells in the pancreas . Insufficiency of insulin in the body results in diabetes . Insulin was one of the first products to be manufactured using genetic engineering .
..... Click the link for more information. , and estrogen estrogen (ĕs`trəjən)
..... Click the link for more information. and other sex hormones; psychotherapeutics such as antianxiety drugs antianxiety drug, drug administered for the relief of anxiety . Although their action is not fully understood, most antianxiety medications appear to affect the action of neurotransmitters in the brain (see serotonin and norepinephrine ).
..... Click the link for more information. and antidepressant drugs antidepressant, any of a wide range of drugs used to treat psychic depression . They are given to elevate mood, counter suicidal thoughts, and increase the effectiveness of psychotherapy .
..... Click the link for more information. ; cortisone cortisone (kôr`tĭsōn'), steroid hormone whose main physiological effect is on carbohydrate metabolism.
..... Click the link for more information. and synthetic corticosteroid drugs corticosteroid drug (kôr'təkōstâr`oid)
..... Click the link for more information. used in treating inflammatory diseases such as arthritis; vitamins and dietary minerals; antidotes for poisons; and various drugs that act as stimulants stimulant, any substance that causes an increase in activity in various parts of the nervous system or directly increases muscle activity. Cerebral, or psychic, stimulants act on the central nervous system and provide a temporary sense of alertness and well-being as
..... Click the link for more information. or depressants depressant, any one of various substances that diminish functional activity, usually by depressing the nervous system . Barbiturates , sedatives , alcohol, and meprobamate are all depressants. Depressants have various modes of action and effects.
..... Click the link for more information. on all or various parts of the nervous system, including analgesics analgesic (ăn'əljē`zĭk), any of a diverse group of drugs used to relieve pain.
..... Click the link for more information. , narcotics narcotic, any of a number of substances that have a depressant effect on the nervous system. The chief narcotic drugs are opium , its constituents morphine and codeine , and the morphine derivative heroin .

See also drug addiction and drug abuse .
..... Click the link for more information. , amphetamines amphetamine (ămfĕt`əmēn), any one of a group of drugs that are powerful central nervous system stimulants .
..... Click the link for more information. , and barbiturates barbiturate (bärbĭch`ərāt'), any one of a group of drugs that act as depressants on the central nervous system .
..... Click the link for more information. (see also anesthesia anesthesia (ănĭsthē`zhə) [Gr.
..... Click the link for more information. ; psychopharmacology psychopharmacology (sī'kōfär'məkŏl`əjē)
..... Click the link for more information. ; hallucinogenic drug hallucinogenic drug (həl
..... Click the link for more information. ).

See also drug resistance drug resistance, condition in which infecting bacteria can resist the destructive effects of drugs such as antibiotics and sulfa drugs . Drug resistance has become a serious public health problem, since many disease-causing bacteria are no longer susceptible to
..... Click the link for more information. ; drug poisoning drug poisoning, toxic effects caused by an administered drug. Worldwide more than 9 million natural and synthetic chemicals have been identified; fewer than 3000 cause more than 95% of acidental and deliberate poisonings.
..... Click the link for more information. ; drug addiction and drug abuse drug addiction and drug abuse, chronic or habitual use of any chemical substance to alter states of body or mind for other than medically warranted purposes.
..... Click the link for more information. .

Sources of Drugs

Drugs are obtained from many sources. Many inorganic materials, such as metals, are chemotherapeutic; hormones, alkaloids, vaccines, and antibiotics come from living organisms; and other drugs are synthetic or semisynthetic. Synthetics are often more effective and less toxic than the naturally obtained substances and are easier to prepare in standardized units. The techniques of genetic engineering genetic engineering, the use of various methods to manipulate the DNA (genetic material) of cells to change hereditary traits or produce biological products.
..... Click the link for more information. are being applied to the production of drugs, and genetically engineered livestock that incorporate human genes are being developed for the production of scarce human enzymes and other proteins (see pharming pharming (fär`mĭng), the use of genetically altered livestock, such as cows, goats, pigs, and chickens, to produce medically useful
..... Click the link for more information. ).

Pharmacopoeia and Drug Safeguards

Standards for drugs and tests for their identity, quality, and purity are given in the U.S. pharmacopoeia pharmacopoeia or pharmocopeia (fär'məkəpē`ə)
..... Click the link for more information. , first published in 1820 and at first revised every 10 years, later every 5 years. The British publish a similar pharmacopoeia. The National Formulary published by the American Pharmaceutical Association gives the composition, description, method of preparation, and dosage for drugs; the Physician's Desk Reference is a privately published compilation of information supplied by drug companies about their drug products, published yearly. The scientific study of drugs, their actions and effects, is pharmacology pharmacology, study of the changes produced in living animals by chemical substances, especially the actions of drugs , substances used to treat disease. Systematic investigation of the effects of drugs based on animal experimentation and the use of isolated and
..... Click the link for more information. .

Legislation to safeguard drug purchasers began in the United States with the Pure Food and Drugs Act of 1906; this was superseded by the more inclusive and more stringent federal Food, Drug, and Cosmetic Act of 1938. Such laws are enforced by the Food and Drug Administration. The 1962 Kefauver-Harris amendments to the Food, Drug, and Cosmetic Act increased the authority of the Food and Drug Administration to regulate testing and marketing of new drugs. There are two marketing classes of drugs: ethical drugs, for which prescriptions are needed, and proprietary drugs, which are sold over the counter without prescription. Many of the latter, such as mouthwashes, gargles, and cold preparations, are only slightly, if at all, effective in curing ailments.

Bibliography

See B. Barber, Drugs and Society (1967); C. B. Clayman, ed., American Medical Association Guide to Prescription and Over-the-Counter Drugs (1988); A. Burger, Drugs and People: Medications, Their History and Origins, and the Way They Act (rev. 1988); United States Pharmacopeial Staff, The Complete Drug Reference (1995).