[Comparative serum pharmacokinetics of prednisone and prednisolone methylsulfobenzoate after oral administration].

Pharmacokinetic values of prednisone and prednisolone were measured in the serum of 6 healthy volunteers after oral administration of either prednisolone methylsulfobenzoate 30 mg or prednisone 30 mg. Peak serum concentrations of prednisolone obtained after dosing with prednisone occurred earlier and were higher (473 +/- 106 ng/ml) than those obtained after dosing with prednisolone methylsulfobenzoate (232 +/- 70 ng/ml; P less than 0.01). Similarly, areas under the 0-8 h concentration curves were significantly greater after dosing with prednisone than after dosing with prednisolone methylsulfobenzoate (prednisolone: P less than 0.001; prednisone: P less than 0.02). The differences may be due to prednisolone methylsulfobenzoate not being absorbed as well as prednisone. These kinetic data may warrant a reappraisal of the therapeutic equivalence of the two drugs taken for granted in France.