NEW DELHI: Men could have more contraceptive choices beyond condoms and vasectomy, with the World Health Organization (WHO) releasing its first global blueprint for developing novel male contraceptives, including daily pills or gels, longer-acting injections and implants, sperm-function blockers and reversible methods that block sperm transport.
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The WHO's Target Product Profiles (TPPs) do not approve or launch any new contraceptive. Instead, they set minimum and optimal standards for the effectiveness, safety, reversibility, acceptability and affordability of future male contraceptives. The framework covers three approaches: suppressing sperm production, inhibiting sperm function and blocking sperm transmission or transport.
The move comes as research into male contraception gathers pace, with several candidates already in clinical trials. RISUG (reversible inhibition of sperm under guidance), developed in India, has completed Phase 1 and Phase 2 studies, while another hydrogel-based method, ADAM, is in Phase 1 trials. Hormonal candidates including nestorone/testosterone gel, dimethandrolone undecanoate (DMAU) and 11β-methyl-19-nortestosterone dodecylcarbonate (11β-MNTDC) are also being investigated.
For methods that suppress sperm production, WHO's minimum target is for 90% of men to achieve sperm concentrations of 1 million or fewer sperm per millilitre within 12 weeks, with a 12-month cumulative pregnancy rate of no more than 7%. The optimal target is 95% achieving this level within eight weeks, with the pregnancy rate at 3% or less.
The proposed methods include daily tablets or gels, injections every three, six or 12 months and implants lasting at least a year. WHO's optimal profile also calls for sperm concentrations to return to the normal reference range within six months of stopping treatment.
Another strategy is to leave sperm present but disable functions needed for fertilisation, such as motility and capacitation. A third is to block sperm transport through the vas deferens, potentially using reversible hydrogels, or temporarily block ejaculation with medication.
WHO said the field is rapidly progressing, with several candidates in advanced clinical trials. The new profiles are intended to provide developers and regulators with a common framework for bringing future male contraceptives through research and development.
