ABSTRACT
Prodrug is a term used by Albert to describe a com pound which must undergo bio conversion prior to exerting its pharmacological effect (Albert 1958; 1964). The term, as applied here, will refer to a drug with a covalently bound, inactive moiety (the promoiety) which provides the desired pharm aceutical properties, where the promoiety must be removed upon administration to regenerate the parent drug. Enzymatic and chemical processes are available for removal of the inactive moiety, and these may guide or limit the selection of the promoiety. As an example, esterases are present throughout the body and can be utilized in the hydrolysis of an ester functional group in a prodrug for a drug bearing a carboxylic acid or an alcohol group (Colaizzi and Pitlick 1982). The reconversion of the prodrug to the parent com pound by an enzy matic means requires that the enzyme be capable of cleaving the promoiety-drug linkage. Chemical reversal, in vitro or in vivo, may dem onstrate less intersubject vari ability than do methods that rely on biochemical routes (Notari 1985).
