Male Reproductive Pharmacology

According to the United Nations, there are over 200 million pregnancies around the world each year and 121 million of these are unwanted. While present contraceptive methods are very effective, an increased number of options for contraception would almost certainly decrease the number of unwanted pregnancies. Thus, there is clearly a need to develop additional methods of contraception for males, a market which is clearly lacking. Presently, the main form of male contraception are condoms, the only other method of male contraception is surgical vasectomy. Vasectomy is very successful but has the drawback of being very difficult to reverse rendering this option unappealing to young men who may wish to have a family in later life.

The quest for better male contraceptives has been a major medical challenge for many years. Most strategies have focussed on hormonal strategies to reduce sperm production or germline strategies to produce dysfunctional sperm that are incapable of fertilization. The problem with hormonal approaches is that they have intolerable side effects such as affecting libido, sexual performance and the development of masculine characteristics. In mice, we have genetically demonstrated a male contraceptive target within the autonomic nervous system, which would not affect the long term viability of sperm nor the sexual or general health of males. Due to the nature of this target, the contraceptive has the potential to be orally administered and readily reversible. This is a strong finding of great impact but the next step is to show the same effect on fertility using pharmacological agents.