Screening for formation of drug molecule

                                   Random screening

In this method all compounds i.e. both synthetic chemical and plant /animal/ marine product from given series were tested

E.g., in 1940 when scientific community learned about anti bacterial action of penicillin , large scale systemic random screening result in screening of more than 6×103 antibiotics,, 100 of which are used in medicine.

Advantage: - Antibiotics streptomycin & tetracycline  were found out by this method

Disadvantage:-

• non economical
• over use of man power

1) A variation of this approach is “rationally directed random screening”. (Isolation and identification of product of drug metabolism)

2) It seen that several drugs are themselves in active but their metabolites are active. This metabolites were isolated and identified and introduced as were isolated and identified and introduce as drugs

Eg acetanilide and acetophentidine are metabolized to active acetaminophen which exert main analgesic action for this reason acetaminophen itself was introduced into therapeutics.