Pharmacokinetics of diltiazem in patients undergoing continuous ambulatory peritoneal dialysis

The disposition of a single oral dose of diltiazem hydrochloride was studied in six male patients treated by continuous ambulatory peritoneal dialysis. Peak concentrations were obtained 2 to 4 hours postdose. The mean absorption rate constant was 0.94 +/- 0.21 (sd) hr-1, and the mean elimination half-life was 3.09 +/- 1.16 hr. Serum levels of deacetyldiltiazem, a metabolite of diltiazem, were always below 10 ng/mL. The amounts of diltiazem and deacetyldiltiazem eliminated in dialysate over 24 hours represent less than 0.1% of the administered dose. The pharmacokinetic parameters of diltiazem determined in these patients did not differ from those determined in healthy volunteers and in patients suffering from end-stage renal disease.