Pharmacokinetics and haemodynamics of candesartan cilexetil in hypertensive patients on regular haemodialysis

Aims The pharmacokinetic profile of candesartan cilexetil might be altered in patients with end-stage renal disease (ESRD). No data are available about the pharmacokinetics and haemodynamics of the angiotensin II receptor antagonist candesartan cilexetil in ESRD patients on regular haemodialysis (HD). Methods We performed a repeated dose study (8 mg candesartan cilexetil once daily) in eight male HD patients over a treatment period of 5 days with an additional observation period of 3 days. Results Pharmacokinetic analysis with nonlinear mixed effects modeling (NONMEM) over the whole treatment period revealed a dependency of the volume of distribution on body weight and of the metabolic clearance on age and body weight in the studied population. No significant drug elimination by HD was observed. The estimated metabolic and intercompartmental clearances were 83 ml min(-1) (CV 39%) and 9.9 ml min(-1), respectively. The unexplained random variability of the final two compartment model was 30%. In one patient with adult polycystic kidney disease oral clearance decreased during the observation period, attributable to a significant increase in bioavailability. Maximum observed changes in blood pressure were -50/-27+/-14/8 mmHg on day 5 with haemodialysis therapy as compared with changes in blood pressure of -14/-12+/-14/8 mmHg on day 1 without haemodialysis treatment, The observed maximum decrease in systolic blood pressure correlated with the amount of ultrafiltration during the HD session on day 5 (r = 0.70, P < 0.05). In two patients, one of whom was binephrectomized, severe hypotensive episodes were observed during this HD session. Conclusions HD does not influence the elimination kinetics of candesartan. The observed inter- and intraindividual variability of oral clearance and the pronounced influence of HD-induced volume contraction on the haemodynamic effects of candesartan makes it mandatory to carefully monitor HD patients treated with candesartan cilexetil.