Pharmacokinetics of tiapride and absolute bioavailability of three extravascular forms

The pharmacokinetic properties of a single 200-mg dose of tiapride were studied in eight healthy volunteers (four males and four females). The drug was administered by i. v., i. m., and p. o. routes (solution and tablets). Plasma and urine concentrations were determined by a high-performance liquid chromatography. The results were compatible with a linear two-compartment model. The half-life in the disposition phase ranged from 2.19 h to 4.55 h (mean 3.23 h). Peak plasma concentrations were always reached within 2 h. The percentage of absorption of the i. m. and the two p. o. formulations varied from 49.3 to 98.9%. The renal clearance varied from 11.8 to 24.9 l/h. The drug was mainly eliminated in unmetabolized form in the urine (75.6%).