Pharmacokinetics of Quinapril Hydrochloride in Rats and Dogs.

Abstract

After oral administration of quinapril hydrochloride (3 mg/kg) to rats and dogs, the unchanged drug, its active metabolite (quinaprilat) and the diastereomers of quinaprilat in plasma were simultaneously analyzed using the gas chromato graph-negative ion chemical ionization mass spectrometer. The obtained results are as follows: (1) In rats, the plasma concentration of quinaprilat reached the maximum (Cmax) of 2.48 μg/ml at 0.38 hr after oral administration, and then disappeared with the terminal half-life (t1/2z) of 33.9 hr. The unchanged drug in plasma was not detected throughout all the time point examined. The bioavailability of quinaprilat was 63.4%. (2) In dogs, the plasma concentration of unchanged drug reached the Cmax of 0.41μg/ml at 0.42 hr and that of quinaprilat reached the Cmax of 3.51 μg/ml at 0.92 hr after oral administration. The unchanged drug in plasma quickly disappeared and quinaprilat disappeared with the t1/2z of 16.8 hr. The bioavailability of quinaprilat was 47.1%. (3) There were no changes in the configuration of quinapril and quinaprilat after oral administration to rats and dogs.