A number of articles have been published which look at options for male contraceptives. Apart from condoms and vasectomy, no other methods are currently available to men. Various methods have been examined including pills, patches, injections and implants. There are also trials looking at a gel that is injected into the vas deferens and an intra vas 'plug' device, both of which would result in long-term infertility but have the potential advantage of being reversible.
It was in the early 1990s that studies were first published showing testosterone could sufficiently suppress sperm production to act as a viable contraceptive. These studies, sponsored by the World Health Organization (WHO), established that hormonal methods could be effective for men, and secondly, defined the level to which sperm counts need to be suppressed to act as a reliable contraceptive.
The most promising approach seems to be the administration of a long-acting testosterone by implant or injection, coupled with an implanted or injected progestogen. This would act to suppress luteining hormone (LH) and follicle stimulating hormone (FSH) from the pituitary which would then suppress spermatogenesis.
The combination of long-acting testosterone and progestogen seems better that testosterone alone as it reduces the dose of testosterone required, thus decreasing the side-effects of a high steroid load. Also, spermatogenesis is not suppressed to zero in all men by testosterone alone (particularly in non Asian men, the reason for his being unclear), and adding in progestogens and/or gonadotropin-releasing hormone (GnRH) antagonists further suppresses pituitary gonadotropins thus optimizing contraceptive efficacy.
Current combinations of testosterone and progestogens completely suppress spermatogenesis in 80-90% of men without severe adverse effects, with significant suppression in the remainder of individuals. Recent trials with newer, long-acting forms of injectable testosterone which can be administered every eight weeks, combined with progestogens administered either orally or by long-acting implant, have yielded promising results too.
A multicentre study investigating subcutaneous etonogestrel implants with injectable testosterone decanoate as a potential long-acting male contraceptive looked at 130 subjects who were randomised to having 2 etonogestrel rods (204mg) plus:
For a treatment period of 48 weeks. In group 1 (n=42), sperm concentration was less than 1 x 106 per ml by week 24 in 90% of the participants. In group 2 (n=51) this was achieved by 82% at 24 weeks, and in group 3 (N=37) by 89%. 110/130 men completed 48 weeks of treatment. 14/130 men discontinued treatment due to side-effects.
Mean haemoglobin levels increased in group 1, and a non-significant increase in weight and decline in high-density lipoprotein cholesterol was observed in all groups. This is a particularly important factor to study, knowing the already present male susceptibility to arterial disease. Efficacy of suppression was less in group 2, probably due to inadequate testosterone dosage.
So, it is feasible that a male contraceptive will be made available to the community in the near future.
The ideal contraceptive
Guillebaud's features (see references) of the ideal contraceptive are that it would be:
No method (other than abstinence) is 100% effective. The WHO has established guidance as to the level of sperm suppression needed. Implants and injections are certainly more forgettable than pills, intra-vas methods moreso again.
All methods discussed are independent of intercourse.
Sperm counts do normalise when testosterone is stopped.
Side effects of testosterone alone have included acne, weight gain, and suppression of high density lipoprotein (HDL), (reversible on stopping testosterone use). Side effects of combinations of testosterone and/or GnRH antagonists are being monitored in trials at present, but have not been severe. Studies suggest little impact on aggressive behaviour, which was an early concern.
The injections are often given monthly or bimonthly. Little information is available on potential costs.
This is not applicable to injections or implants as they need to be given regularly by trained professionals. Intravas methods, once performed by the medical profession, would offer longer-acting contraception.
When developing female contraceptives, potential side effects can appear minor in comparison with the large health benefits of avoiding unintended pregnancy. In contrast, when developing contraceptive methods for men who do not face the risks of pregnancy and childbirth, the impacts of side effects can appear relatively large. Studies suggest, however, that many men are willing to take on the side effects and health risks of contraceptive use. Studies suggest little impact on men's libido.
Many men and women in surveys, focus groups, and interviews say that they want to share the responsibility for contraception. Studies of the potential acceptability of male hormonal contraception also suggest that women would trust their partners to use the method reliably. WHO supports the development of male methods and recognizes the public health benefits of increased male participation in family planning activities.
References:
Guillebaud J. Contraception - your questions answered. 2003. Churchill Livingstone.
Lohiya N K, et al. Perspectives of contraceptive choices for men. Indian J Exp Biol 2005; 43: 1042-1047.
Rajalakshmi M. Male contraception: expanding reproductive choice. Indian J Exp Biol 2005; 43: 1032-1041.
Amory J K. Male hormonal contraceptives : current status and future prospects. Treat Endocrinol 2005; 4: 333- 341.
Brady B M, et al. A multicentre study investigating subcutaneous etonogestrel implants with injectable testosterone decanoate as a potential long-acting male contraceptive. Hum Reprod 2006; 21: 285-294.