Papaverine hydrochloride in peripheral blood and the degree of penile erection.

Papaverine hydrochloride was injected into the penis in 32 impotent patients, and peripheral blood concentrations were measured at 3, 5, 10, 15 and 30 minutes. The patients then were divided into groups according to the rate of increase of the penile circumference (20% or more complete erection, 10 to 19% and less than 9% groups). Patients with a more complete erection had a significantly lower concentration of papaverine hydrochloride in the peripheral blood at 3 minutes after administration (p less than 0.05). Therefore, patients who do not respond to papaverine have some defect in the venous closure system.