Inhibition of angiotensin-converting enzyme—a new concept of medical treatment of male infertility?

To evaluate the effectiveness of systemic captopril therapy. Randomized double-blind study. Andrology Unit at the Department of Dermatology, University of Munich, Munich, Germany. Infertile men suffering from oligozoospermia (5–20×106 spermatozoa/mL) and/or asthenozoospermia. Captopril was given orally; samples of seminal plasma were collected twice before treatment and 4 and 12weeks after captopril administration. Semen parameters, pregnancy rate, ACE activity, and kinin levels. After 4weeks of therapy, significant differences between verum group and placebo group were found concerning ACE activity and kinin levels. Sperm density improved significantly after 12weeks of captopril therapy. All other semen parameters remained unchanged. The pregnancy rate was not improved. The suitability of captopril in the therapy of oligozoospermia and/or asthenozoospermia for improvement of male infertility seems to be limited.