Use of low-dosage oral cyproterone acetate as a male contraceptive.

To ascertain the effects of low-dosage cyproterone acetate (CPA) on the reproductive and endocrine functions of normal men, 25 volunteers were given CPA 0, 5 or 10 mg daily over 16 weeks, preceded by 12 weeks pretreatment observation and followed by 24 weeks posttreatment follow-up. CPA caused a decrease in sperm concentration, percentage motility, proportion of normal sperm and ability of the sperm to penetrate a column of cervical mucus in most patients. In addition, circulating testosterone, estradiol, LH and FSH levels were significantly reduced during treatment. All these changes reverted to the pretreatment level upon drug withdrawal. These findings suggest that firstly, although low dosage CPA was able to induce changes in seminal analyses, azoospermia was present in only one out of 15 subjects exposed to the drug. Secondly, the marked decrease in androgen levels associated with CPA treatment renders CPA unsuitable as a single entity agent for long-term male contraception.