IN VITRO AND IN VIVOMETABOLISM OF PREDNISOLONE: STUDIES CONCERNING ITS BIOLOGICAL EFFECTIVENESS

Abstract

Metabolism of prednisolone by rat liver microsome-supernatant fractions has been reinvestigated. It has been found that both C-20 and [DELTA] 4-3 ketone reduction of prednisolone is considerably slower than rates of reduction of these substituents on the hydrocortisone molecule. Comparisons of glycogenic activity also resulted in collection of data which suggest that prednisolone persists for a longer period in tissues or body fluids of fasted adrenalectomized rats. When equal amounts of either hydrocortisone or prednisolone were administered intraperi-toneally to fasted adrenalectomized rats, it was found that forty-two times as much unaltered prednisoline appeared in the urine following a 48-hour collection period. The significance of these results in relation to increased biological efficacy of the synthetic steroid is discussed.