PHARMACOLOGY

 SOURCES OF DRUGS ::

Drugs may be obtained from 1.Plants 2.Animals 3.Minerals or 4.Microorganisms The drugs may also be Semisynthetic or Synthetic compounds Amongst all these synthetic drugs i.e. those which are prepared by chemical processes are used most widely because they are cheap ease of quality control mass production and therapeutic efficacy Recently biotechnology has emerged out as one of the important sources for drugs 

1.Drugs from plant source :: There  is a vast vegetative flora (indegenous source ) from which leaves flowers fruits roots stems seeds barks wood bulbs etc are being used as drugs Crude drugs are treated to isolate their active principles They in turn are purified identified and wherever possible used as drugs for example from the leaves of foxglove the cardiac glycosides are isolated viz digitalis poppy capsule gives opium cinchona bark yields quinine etc 

2.Drugs from animal source :: Liver endocrine glands and secretory organ of animals are used to extract active constituents e.g. liver extract insulin thyroxine and pepsin etc 

3.Drugs from mineral source :: This comprises of metals and non - metals with their salts mineral acids etc e.g. iron zinc aluminium mercury etc in the form of salts Hydrochloric acid (dilute) is an example of a mineral acid 

4.Micro-organisms :: The substrances isolated from micro organisms are used in high dilution to kill or prevent growth of other microbes citric acid etc These substances are known as antibiotics e.g. penicilin streptomycin etc 

5.Semi-synthetics :: Many a times the drugs obtained from natural sources may not serve the purpose with respect to potency specificity duration of action or may even produce adverse effects The substances obtained by chemical modification of the naturally occurring compounds are called semi-synthetic compound e.g. methylscopolamine bromide from scopolamine homatropine from atropine and heroin from morphine 

6.Synthetics :: Synthetics are drugs that are synthesised by chemical processes Phytochemical investigations give us the clue to synthesise identical compounds in the laboratory once the chemical and structural formula are established it becomes easy to prepare or manufacture large bulk as well as to maintain uniformity of standard and control the quality Synthetic drugs naturally become comparatively cheap and can be synthesised quickly when desired Examples of synthetic drugs are chloroquine acetylsalicylic acid chlorpromazine homatropine sulpha drugs ephedrine etc 

7.Drugs obtained through biotechnology or Genetic Engineering :: biotechnology is the use of microbes plants or animal cells in the production of a wide variety of drugs which are presently safely derived from animal or human source for example genes encoding penicilin biosynthesis enzymes introduced into new host bacterium 

    Human insulin is now obtained by recombinant DNA technology wherein gene manipulation is done and the modified gene is introduced into protozoa that in turn produces purer form of insulin