Biopharmaceutic and pharmacokinetic aspects of vincamine HCl.

Vincamine HCl was biopharmaceutically and pharmacokinetically evaluated. For biopharmaceutical characterization of the drug the apparent lipoid/water partition coefficient (APC), pKa, extent of protein (bovine) binding and the erythrocyte (human) uptake were determined. Vincamine has an APC of 2.05, a pKa of 6.17, is 64% bound to plasma proteins, and is about 6% bound to erythrocytes. Because the gerbil was used as model in pharmacodynamic studies, the pharmacokinetic drug disposition was determined in this species and compared to parameters reported in the literature for other species. The terminal half-life is about 1 hour, the apparent volume of distribution 2.9 L/kg, and the total clearance is about 33.3 ml/min/kg. The parameters are comparable to other species including man. The brain concentration is about 5-fold that in plasma. A therapeutic steady state concentration for effectiveness in gerbils has been estimated to be 0.02 mcg/ml.