Women have a large number of effective and reversible contraceptive methods to choose from.

For men, however, the choice is limited to the condom, vasectomy and coitus interruptus (withdrawal).

Men are clearly prepared to take responsibility for contraception. About one quarter of all couples world-wide rely on these methods of male contraception.

It is therefore a challenge for science and research to provide men with a contraceptive method which is at least on a level with hormonal contraceptives as regards efficacy and tolerability.