An injected male contraceptive may be on the way – with the ability to block fertility by increasing testosterone levels.
The hormone jab was developed by a team at the National Research Institute for Family Planning in Beijing, China. They say that the monthly injection could be just as effective as the female pill or condoms.
The team, led by Dr Yi-Qun Gu, explains in the Journal of Clinical Endocrinology & Metabolism that there are few large-scale studies of hormonal male contraceptives. They tested the safety, effectiveness and feasibility of injectable testosterone undecanoate on 1,045 healthy fertile Chinese men.
The men received 500mg of this form of testosterone each month for 30 months. Sperm suppression and pregnancy rates in partners were measured. Among the men, 4.8 per cent did not reach the low levels of sperm production required for effective contraception.
Nine pregnancies occurred during the study, which equates to a contraceptive failure rate of 1.1 per 100 men. There were no serious side-effects, and normal sperm production resumed six months after the study for all but two of the men. However, almost a third of the men did not complete the study, and no reason was given.
The researchers conclude: “Monthly injection of 500mg testosterone undecanoate provides safe, effective, reversible and reliable contraception in a high proportion of healthy fertile Chinese men.”
Dr Gu commented: “For couples who cannot, or prefer not to use only female-orientated contraception, options have been limited to vasectomy, condom and withdrawal. Our study shows a male hormonal contraceptive regimen may be a potential, novel and workable alternative.”
More studies are needed to confirm the safety of the injection.
Gu, Y. et al. Multicenter Contraceptive Efficacy Trial of Injectable Testosterone Undecanoate in Chinese Men. The Journal of Clinical Endocrinology & Metabolism, June 2009; DOI: 10.1210/jc.2008-1846.
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