Effect of cyproterone acetate on sperm concentration, seminal fluid volume, testicular cytology and levels of plasma and urinary ICSH, FSH and testosterone in normal men.

Cyproterone acetate (CA) was administered to a group of 6 normal healthy males in 2-100 mg doses daily continuously for a period of 16-20 weeks in order to test the effect of CA on the male reproductive system. This dosage is the norm for treatment of benign or malignant prostatic hypertrophy. Sperm counts fell off after an average of 8 weeks experimentation and reached the level of functional sterility by an average of 13 weeks. Morphological abnormality of the sperm increased over time. Sperm motility decreased. Libido and potency decreased sharply. All these functions returned to normal within a few weeks after administration of CA was stopped. The drug also caused moderate decreases in testicular germ cell numbers and testosterone levels of plasma and urine. No changes resulted in levels of plasma or urinary interstitial cell-stimulating hormone follicle stimulating hormone or in Leydig cell morphology or number. Liver and kidney functions continued normally. Indications are that the major site of inhibition is in the testis not in the epididymis or ductular system. Reduced testosterone level even without androgen deprivation could cause all of these changes. The indication is that CA is a powerful antifertility agent. The undesirable effects of loss of libido and impotency may be abolished by reducing the dosage. By maintaining a dosage of sufficient strength CA could be used as a male contraceptive.