Hormonal contraceptives for women have become the benchmark for the safety and effectiveness of birth control methods.

If a male contraceptive method is to be developed which (like the female pill) suppresses the developement of the germ cells, there is a biological hurdle which must be overcome:

While the female pill suppresses the maturing and release of a single egg per month, in men production of 70 to 100 million sperm daily has to be suppressed.

Hormonal Suppression of Sperm Production

Sperm production in the seminiferous tubules of the testes is controlled by testosterone. Production of testosterone in the testes is in turn controlled by the hypothalamus (a region in the diencephalon) and the pituitary (a small gland at the base of the brain).

Administration of a progestin (a class of sex hormones) in men suppresses the activity of the hypothalamus and pituitary. Production of testosterone in the testes stops and there is therefore insufficient testosterone in the seminiferous tubules for sperm production.

However, as testosterone has many other important functions in the male body (e.g. maintaining libido, potency, muscle strength, healthy bones), the reduced testosterone production could lead to deficiency symptoms.
Therefore additional testosterone must be administered - in a dose large enough to maintain libido, potency and general health but not large enough to stimulate sperm production in the testes.

Status of Development

Unfortunately the hormones progestin and testosterone are not sufficiently effective if they are administered by mouth in the form of a pill.

The combination of a progestin implant and a testosterone injection is currently being tested in a large clinical trial. The first results are very promising. Schering is working on this project together with the company Organon.

Development of a marketable product is expected to take several years.