The alpha-adrenergic blocking action of prazosin hydrochloride on the canine urethra.

We studied the action of prazosin hydrochloride on the canine urethra by measuring urethral pressure profiles, employing both oral and intravenous preparations. Its interaction with intravenous ephedrine sulfate was determined. Prazosin hydrochloride produced a marked depressant effect on the maximum urethral pressure and the urethral pressure profile. It antagonized the effect of intravenous ephedrine sulfate. We believe that the effects of prazosin hydrochloride are caused by alpha-adrenergic blockade and that application of this drug to human voiding dysfunction should be considered.