Overcoming challenges associated with the bioanalysis of an ester prodrug and its active acid metabolite

Aim: Bioanalysis of ester prodrugs represents a great analytical challenge due to poor matrix stability in the presence of esterases. Materials & methods: An approach that includes pH control, temperature and the use of an inhibitor (sodium fluoride, NaF) was employed for complete stabilization of an ester prodrug and its corresponding acid metabolite. Stability information was used to design a methodology with negligible ex vivo hydrolysis of the ester to the corresponding acid analyte during all critical parts of bioanalysis. Results & conclusion: The assay was fully validated to regulatory expectations and employed to support a preclinical Good Laboratory Practice study in rats....