Quinapril is a prodrug and non-sulfhydryl angiotensin converting enzyme (ACE) inhibitor with antihypertensive activity. Quinapril is hydrolized by carboxylesterases, into its active form quinaprilat, which binds to and inhibits ACE, thereby blocking the conversion of angiotensin I to angiotensin II. This abolishes the potent vasoconstrictive actions of angiotensin II and leads to vasodilatation. Quinapril also causes a decrease in angiotensin II-induced aldosterone secretion by the adrenal cortex, thereby promoting diuresis and natriuresis, and increases bradykinin levels.
AIM: The aim of the present study was to investigate the effects of the carboxylesterase 1 (CES1) c.428G > A (p.G143E, rs71647871) single nucleotide variation (SNV) on the pharmacokinetics of quinapril and enalapril in a prospective genotype panel study in healthy volunteers. METHODS: In a fixed-order crossover study, 10 healthy volunteers with the CES1 c.428G/A genotype and 12 with the c.428G/G genotype ingested a single 10 mg dose of quinapril and enalapril with a washout period of at least 1 week. Plasma concentrations of quinapril and quinaprilat were measured for up to 24 h and those of enalapril and enalaprilat for up to 48 h. Their excretion into the urine was measured from 0 h to 12 h. RESULTS: The area under the plasma concentration-time curve from 0 h to infinity (AUC0-infinity ) of active enalaprilat was 20% lower in subjects with the CES1 c.428G/A genotype than in those with the c.428G/G genotype (95% confidence interval of geometric mean ratio 0.64, 1.00; P = 0.049). The amount of enalaprilat excreted into the urine was 35% smaller in subjects with the CES1 c.428G/A genotype than in those with the c.428G/G genotype (P = 0.044). The CES1 genotype had no significant effect on the enalaprilat to enalapril AUC0-infinity ratio or on any other pharmacokinetic or pharmacodynamic parameters of enalapril or enalaprilat. The CES1 genotype had no significant effect on the pharmacokinetic or pharmacodynamic parameters of quinapril. CONCLUSIONS: The CES1 c.428G > A SNV decreased enalaprilat concentrations, probably by reducing the hydrolysis of enalapril, but had no observable effect on the pharmacokinetics of quinapril.
