SOURCES OF DRUGS

1) NATURAL a) Plants Oldest source of drugs used empirically Leaves, seeds, flowers, roots, bark etc Problems: Identification of plant Climatic and social conditions of area Season of collection Condition of storage cont.

 Standardization of active principle  Purity of active ingredient  Maintenance of supply line  Active principle is synthesized after detection e.g. morphine, codeine, digitalis, quinine, atropine, reserpine and pilocarpine

VARIOUS FORMS OF PLANT DRUG  Extract, infusions, decoction, powders etc  Chemicals (alkaloids, glycosides, oil, resins, tannins, gums etc.) isolated from different forms are used for humans and animals, c/d active principles

b) Animals  Modern drugs  Active principles are proteins, oil and fats, enzymes and hormones  e.g. gonadotropins, heparin, insulin, thyroid extract and enzymes

c) Microorganisms  Antibiotics derived = fungi and bacteria after discovery of penicillin in 1928 and its use in 1940  Use for infective diseases  E.g. penicillin, streptomycin, tetracycline, chloramphenicol and erythromycin

d) Minerals  Metals, metalloids, non-metal subs. and their compounds  E.g. iron, calcium, magnesium, aluminium, sodium, potassium, sulphur, lithium etc

2) SEMI-SYNTHETIC  Complex molecules  Expensive and for impure natural compound  E.g. 6-aminopencillanic acid (fungus), semi-synthetic human insulin (pork insulin)

4) SYNTHETIC  Pharmaceutical laboratory  Organic or inorganic or combination of organic and inorganic compounds  >90% drugs  E.g. older drug; chloroform, ether, nitrous oxide, chloral hydrate  Antipyretics, sulphonamides, antihistamines, anticonvulsants, anti anxiety etc

RECOMBINANT DNA TECHNOLOGY  Human insulin human proinsulin gene cDNA E.coli treat proinsulin to form insulin  Growth hormone, tissue plasminogen activator, vaccines, interferon, erythropoitins, G-colony stimulating factor