Prazosin, pharmacokinetics and concentration effect.

The pharmacokinetics and effects of prazosin have been studied after intravenous and oral dosing (1 mg) to 6 normal male volunteers. The mean terminal (beta) half-life was 2.9 h after intravenous and oral routes. Oral bioavailability was 56.9%. The effects of prazosin on blood pressure were more pronounced after intravenous than oral administration, and the hypotensive effect greater on erect blood pressure. There was a significant correlation (P less than 0.02) between the fall in blood pressure and the plasma drug concentration after intravenous prazosin.