A pharmacokinetic comparison of two oral liquid glucocorticoid formulations

To compare pharmacokinetics of liquid prednisolone and prednisone solutions and to assess relative bioavailability, six healthy adult men were administered 15 mg of each formulation. Blood samples were obtained and assayed for plasma prednisolone concentrations by high-performance liquid chromatography. Peak concentration was significantly higher with liquid prednisolone (mean +/- SD 430.3 +/- 62.5 vs 333.0 +/- 27.8 ng/ml, p = 0.013), with similar times to peak concentration. Prednisolone liquid gave higher concentrations at every time point (statistically significant for all except 0.25 hrs after the dose), resulting in a significantly greater total area under the curve (2029.8 +/- 246.9 vs 1633.3 +/- 221.1 ng/ml.hour, respectively, p = 0.002). Clearance was slower for prednisolone (128.3 +/- 15.1 vs 149.1 +/- 17.6 ml/min/1.73 m2, p = 0.01), and the relative bioavailability of the prednisolone liquid using prednisone liquid as the reference standard was 116 +/- 14%. Thus, prednisolone liquid has similar pharmacokinetic characteristics as prednisone liquid, with improved bioavailability.