Endocrine Abstracts

Prednisolone is widely prescribed in the UK, whereas prednisone is used instead for the same indications in the United States. Both have utility as anti-inflammatory agents and for use as glucocorticoid replacement therapy at lower doses. Oral prednisone is converted to prednisolone by first pass hepatic metabolism by 11 beta HSD-1. This study was undertaken to compare the bioavailability of prednisone against prednisolone. To determine the conversion of prednisone to prednisolone, two ‘day curves’ were completed in a healthy volunteer, given 10 mg oral prednisone (USP) and 10 mg oral prednisolone (BP) on two consecutive days. Serum prednisolone levels were checked by uPLC-LCMS/MS. The glucocorticoid dose was administered at 7am on both days. Subsequent blood sampling was completed at fixed time-points until 10 hours post-dose. Prednisone and prednisolone (10 mg) were rapidly absorbed achieving Tmax at 1 hour. The 8h levels were 37 mg/l and 35 mg/l for prednisone and prednisolone respectively. The area-under-the-curve for prednisone and prednisolone was 830.6 mg.h/l and 820.5 mg.h/l, equating to a bioavailability of 101.2%. Terminal half-life was comparable at 2.65h and 2.93h for prednisone and prednisolone respectively. There was no difference in the day curves between Prednisone and Prednisolone, indicating bioequivalence of both formulation. This should not be confused with METHYL prednisolone, which is 20% more potent than both prednisolone and prednisone. So 4 mg METHYL prednisolone is equivalent to 5 mg of prednisolone and 5 mg prednisone. In countries where prednisolone is not available, an equivalent dose of prednisone can be used.