Antispermatogenic action of gossypol in men.

Twelve Brazilian men were treated with gossypol for 1 year. The treatment schedule consisted of oral administration of 20 mg gossypol daily for 4 months, followed by a maintenance dose of 20 mg on alternate days (3 days a week), totaling 60 mg weekly for 8 months. Ten men became azoospermic at the end of the fourth month of treatment, and the two others developed marked oligospermia with necrospermia. Except for one man who complained of transient listlessness and fatigue, the subjects reported no side effects during treatment. No changes in libido or potency were reported, and plasma testosterone remained unchanged. Blood chemistry values, which included complete blood cell count, cholesterol, glucose, triglycerides, acid phosphatase, urea, transaminases, sodium, and potassium, were not changed significantly during treatment. The response of the pituitary to gonadotropin-releasing hormone stimulation and the response of the testis to gonadotropin stimulation appeared normal in men treated with gossypol. After treatment, the sperm counts reverted to essentially normal levels in 8 of 12 men. In four men, azoospermia continued 1 year after discontinuation of gossypol treatment. Retrograde phlebography carried out in three of the four men who remained azoospermic after discontinuation of therapy revealed subclinical varicocele.