An evaluation of the pharmacokinetics, pharmacodynamics, and dialyzability of verapamil in chronic hemodialysis patients.

The pharmacokinetics and pharmacodynamics of verapamil were investigated in six chronic hemodialysis patients. A single oral 120-mg dose was administered both on a non-hemodialysis day and a hemodialysis day separated by greater than or equal to 7 days. Blood pressure and PR interval were measured simultaneously with each blood sample. Plasma verapamil and norverapamil concentrations were analyzed by high pressure liquid chromatography. The mean Cmax, tmax, AUC, apparent plasma clearance, and terminal t 1/2 were 190 +/- 108 ng/mL, 0.6 +/- 0.2 hour, 676 +/- 443 ng.hr/mL, 3926 +/- 1933 mL/min, and 11.4 +/- 4.0 hr, respectively, on the nonhemodialysis day. The dialysis clearance of verapamil and norverapamil was negligible. The t 1/2 during hemodialysis was 3.6 +/- 1.1 hr, compared with 3.4 +/- 0.7 hr during the same period of time postdose on the nonhemodialysis day (NS, P greater than .05). Systolic and diastolic blood pressure decreased for up to 4 hours postdose, whereas the PR interval tended to increase. Conclusions include: (1) the single oral-dose pharmacokinetics and pharmacodynamics of verapamil in chronic hemodialysis patients are similar to published data in normal subjects and cardiac patients and (2) verapamil and norverapamil are not significantly removed by hemodialysis, so that supplemental doses are not necessary.