Research Area: Inflammation, Endocrinology Biological Activity: Betapar(Meprednisone) is a glucocorticoid and a methylated derivative of prednisone. [1]The methylprednisone to MPL area under the curve ratio decreased from 0.19 +/- 0.04 in control to 0.14 +/- 0.03 in ketoconazole-treated rats (P less than .05) due to altered interconversion between these steroids. An improved pharmacokinetic/dynamic receptor/gene-mediated model characterized the steroid receptor binding and induction of tyrosine aminotransferase activity after i.v. MPL sodium succinate (10 mg/kg). In contrast to previous in vitro studies, ketoconazole at maximally tolerated doses failed to antagonize the steroid receptor-mediated activity of MPL. [2]