INCOMING GUIDELINES ON CHIRALITY - A CHALLENGE FOR PHARMACOKINETICS IN DRUG DEVELOPMENT

Even though scientific interest regarding enantiomeric purity of chira l drugs is continuously increasing, the availability of enantioselecti ve assays has not developed to a level to resolve all the problems, es pecially those related to pharmacokinetics of chiral drugs active at l ow or very low plasma concentrations. Enantioselective assay in pharma cokinetics of chiral drugs is required in the case of a drug developed as a racemate in order to study the different disposition of individu al stereoisomers and could be also needed in the case of the developme nt of an individual enantiomer to ascertain whether an unidirectional enzyme mediated conversion occurs in the body. A strenuous effort is r equired from pharmacokinetic investigators to study enantioselective p harmacokinetics of chiral drugs, mainly for setting up adequate analyt ical assays. Incoming guideliens on chirality from European, USA and J apan authorities should take into account these difficulties in order to allow the investigators to select the most appropriate design, case by case.