High-performance liquid chromatographic determination of prednisolone and its steroid 21-oate ester derivatives in rat plasma: pharmacokinetic applications.

A high-performance liquid chromatographic (HPLC) technique was developed for the determination of prednisolone and its local anti-inflammatory steroid 21-oate ester derivatives in rat plasma. These new steroid esters (methyl 20 alpha- and 20 beta-dihydroprednisolonate; P4 alpha and P4 beta), developed for local use, were found to exhibit minimal systemic side effects as compared with prednisolone. The described method involves a simple organic extraction procedure and separation of steroids using a C18 reversed-phase column for pharmacokinetic study. The method allows simultaneous measurement of endogenous corticosterone following administration of P4 alpha, P4 beta, and prednisolone. The calibration curves of the steroids were linear over a wide range of concentrations (0.05 to 10 micrograms/mL). The limit of detection of the assay for all tested steroids is 10-20 ng/mL. The method is reproducible, with a coefficient of variation of less than 10% for all steroids over a wide range of concentrations. No interference from endogenous steroids nor exogenous steroids was found. The presented method is simple, rapid, specific, sensitive, and reproducible.