[Problems of male contraception. 2. Male hormonal contraception, post-testicular points of attack, immunization and enzyme inhibition].
In principle control of male fertility is possible by mechanical, surgical and pharmacological methods. However, up to now only the following mechanical and surgical procedures are practicable: coitus interruptus, coitus condomatus and vasectomy. Since the safety of the latter is comparable to the pill, vasectomy is a major alternative to the contraceptive methods used by the female partner. Practical aspects of vasectomy and possible complications are reviewed. Finally, pharmacological approaches and problems involved in the control of male fertility are discussed with special reference to antispermatogenic substances, steroid hormones, immunization and enzyme inhibitors. The concept of antienzymatic contraception is based on the inhibition of penetration of enzymes (acrosin) localized within the acrosomal cap. Unfortunately, penetration of most of the acrosin inhibitors into the acrosome to inactivate acrosin is prevented by the high selectivity of the acrosomal membranes. Thus, pharmacological control of male fertility is still far from being practicable.