RESUMO
Objective of the present study was to investigate the elimination kinetics of quinaprilat and perindoprilat, the active metabolites of angiotensin-converting enzyme (ACE) inhibitors quinapril and perindopril, in hypertensive patients with renal failure under haemodialysis to evaluate the appropriate duration of off-dose of these drugs before starting of low-density lipoprotein (LDL) apheresis. The informed consent was received from 12 hypertensive patients with renal failure, who were under haemodialysis (42 to 62 years). The patients received oral administration of quinapril (10 mg) or perindopril (2 mg) once a day for four weeks. First, to evaluate the dialyzability of each metabolite, blood samples were collected before and after haemodialysis one week after the repeated doses. Second, to evaluate the elimination kinetics of quinaprilat or perindoprilat, blood samples were collected at 24, 72, 120, 192 and 240 h after the final administration. Plasma concentrations of quinaprilat and perindoprilat were measured by high-performance liquid chromatography (HPLC) and radioimmunoassay, respectively. Pharmacokinetic parameters were determined by a model-dependent method. Values of haemodialysis clearance (CL(HD)) and extraction ratio (ER) were 51.5+/-30.2 ml/min and 0.35+/-0.21 for quinaprilat and 108.1+/-5.9 ml/min and 0.75+/-0.04 for perindoprilat, respectively. The terminal elimination half-lives of quinaprilat and perindoprilat were 60.7+/-2.1 and 79.9+/-14.0 h, respectively. The dialyzability of perindoprilat was much higher than that of quinaprilat probably due to low protein binding potency. The present study suggests that hypertensive patients receiving chronic therapy with quinapril or perindopril on haemodialysis should be withdrawn for at least 2 to 3 weeks before LDL apheresis.