prodrug
noun
pro·drug
| \ ˈprō-ˌdrəg
\
\
Medical Definition of prodrug
: a pharmacologically inactive substance that is the modified form of a pharmacologically active drug to which it is converted (as by enzymatic action) in the body
One source of the variability is the metabolism of clopidogrel, which is a prodrug requiring biotransformation to generate its active metabolite.— Jessica L. Mega et al., The Journal of the American Medical Association, 27 Oct. 2010