The importance of pharmacokinetic data on sulpiride: results of a bioequivalence study of two sulpiride 200 mg preparations following oral administration.

In a within-subject comparative trial in 16 healthy volunteers, the bioequivalence of two sulpiride 200 mg preparations was tested using a model-free method of calculation as well as assuming 2- and 3-compartment models. As to AUC act., AUC inf. and Cmax, the test preparation was shown to be significantly superior. Some other differences were found depending on which calculation method was used. The Cmax of the test preparation showed therapeutically relevant plasma concentrations of greater than 400 ng/ml, compared with about 300 ng/ml for the reference preparation. Based upon the raw data obtained, it was the aim of this study to gain further knowledge about other kinetic parameters on which only few data is available. T1/2 beta, clearance, volume of distribution and MRT were calculated using 2- and 3-compartment models. Comparisons with literature data were made and it resulted that a better description of the sulpiride kinetics was obtained when a 3-compartment model was used. Finally, the course of the plasma level was calculated by computer extrapolation assuming a thrice daily administration of sulpiride 200 mg. As a result, steady-state is reached after 3-4 days showing plasma concentrations around 650 ng (reference preparation) and 850 ng (test preparation).