Pharmacokinetics of terazosin, a new selective α₁ blocker, in chronic renal failure patients on hemodialysis

Abstract

The pharmacokinetics of terazosin were studied in 10 patients on chronic hemodialysis. Six of the 10 were given single doses of 0.5mg terazosin orally on dialysis and non-dialysis days. The remaining 4 were given 1mg twice daily orally, for 28 days.
The maximal plasma concentration (Cmax) was 14.2ng/ml and the elimination half life in the beta-phase (t1/2) was 12.7 hours in the case of single administrations. There was no apparent difference in the pharmacokinetics of terazosin between dialysis and non-dialysis days. The dialyzability of terazosin was so low that no terazosin was detected in the dialysate.
Plasma levels of terazosin after repeated administration showed no significant difference over the course of the study. The minimal plasma level ranged from 16.0 to 19.4ng/ml and the maximal plasma level ranged from 23.2 to 30.6ng/ml. No accumulation of plasma terazosin was observed in patients on hemodialysis.
These results suggest that terazosin may be safely administered to patients on chronic hemodialysis without altering the usual dosage regimen.