Metabolites in bioequivalence assessment

M. L. Chen and A. J. Jackson, The role of metabolites in bioequivalency assessment, I. Linear pharmacokinetics without first pass effect, Pharm. Res, 8, 25 (1991). 

I. Mahmood, Assessment of metabolites in bioequivalence studies Should bioequivalence criteria be applied on the sum of parent compound and metabolite , Int. J. Clin. Pharmacol Ther, 36, 540 (1998). 

After oral administration, drug and metabolite concentrations in blood, urine, and feces can easily be monitored. In contrast, topical application to the skin usually aims at a local treatment. Therefore, the main interest lies in determining the drug level within the skin, in order to evaluate the dermal bioavailability of compounds or assess the bioequivalence between different formulations. In the following sections, appropriate analytical techniques will be presented. 

---