Kinetics of methylprednisolone and its hemisuccinate ester

Abstract

Methylprednisolone [cardiovascular drug] in the form of its hemisuccinate ester was injected i.v. in doses of 10 mg/kg and 63.1 mg. Plasma levels of methylprednisolone and of the ester were measured and their kinetics were calculated. Dose dependency in the kinetics of both was indicated. About 10% of the dose was excreted unchanged as hemisuccinate in the urine, indicating incomplete conversion of the prodrug. When methylprednisolone (80 mg) was also taken orally, the relative bioavailability of the tablets was 99%. Saliva levels of methylprednisolone were low but paralleled plasma levels in the postdistribution phase. No methylprednisolone hemisuccinate was found in saliva.