Pharmacokinetics and pharmacodynamics of slow release tablet of diltiazem in hypertensive patients with various renal functions

Twenty hypertensive patients were equally divided into 2 groups: A) with normal renal function (NRF) and B) with impaired renal function (IRF) according to creatinine clearance, blood urea nitrogen and creatinine levels. The pharmacokinetic and pharmacodynamic effects of diltiazem (Dil, 90 mg, bid x 7 d, p.o.) were studied. The pharmacokinetic parameters in IRF patients (Ka 0.7 +/- 0.2 h-1, T 1/2e 3.7 +/- 0.7 h, Cmax1 45 +/- 4 ng.ml-1, Tmax1 3.1 +/- 0.4 h) did not differ from those in NRF patients (0.7 +/- 0.5 h-1, 4.1 +/- 1.3 h, 41 +/- 5 ng.ml-1 and 3.4 +/- 0.4 h, P > 0.05). Antihypertensive efficacy of Dil in patients with IRF was similar to that in those with NRF, and the hypotensive effect lasted over 24 h. The plasma Dil concentrations were strongly correlated with a decrease in BP in both groups. It was concluded that IRF did not affect the disposition of slow release Dil tablet under a steady state. No dosage adjustment of Dil is necessary in hypertensive patients with IRF.