Effects of cyproterone acetate on reproductive functions in normal human males

Daily administration of 5 or 10 mg of cyproterone acetate to normal volunteers over a period of 20 weeks caused a gradual decrease in the count and motility of spermatozoa, concurrently with an increase in the percentage of non-motile as well as abnormal and immature sperms. The ability of motile spermatozoa in the ejaculate to penetrate through the cervical mucus (Kremer's test) was markedly inhibited. The levels of acid phosphatase, sialic acid and glycerylphosphorylcholine in the semen decreased progressively, whereas the levels of fructose did not show any significant change. Libido and potency were not significantly altered. The levels of SGOT, SGPT, serum alkaline phosphatase, blood urea and hematocrit values were not significantly altered. The possible sites and mode of action of cyproterone acetate as well as its potential as a male contraceptive are discussed.