Treating male monkeys with the contraceptive Vasalgel has proved effective at preventing conception amongst rhesus monkeys, reports the California National Primate Research Center.
The report is based on findings from a study that involved sixteen rhesus monkeys that were treated with the contraceptive before being returned to outdoor group housing where female monkeys with successful reproductive histories were also living.
Contraceptive options amongst males have not changed for over a century and the demand for methods other than condom use, withdrawal and vasectomy is growing. Although scientists have discovered new targets, no new products have yet reached the market.
As reported in Basic and Clinical Andrology, Catherine A. VandeVoort and colleagues from the research center administered intravas Vasalgel injections to sixteen sexually mature, male rhesus monkeys . Each male was then returned to outdoor housing, where three to nine females were also housed. All of the females were intact and had histories of successful reproduction. The male monkeys were monitored over at least one breeding season and seven of the 16 were housed with the females on an almost continual basis over two years.
“The purpose of the current study was to put Vasalgel to the ultimate test--preventing pregnancy, not just eliminating sperm--in larger animals more anatomically similar to humans, before human use,” states the report.
The researchers found that none of the females in the group conceived over the two year period.
Complications were minor and included one case of a sperm granuloma developing due to incorrect placement of Vasalgel in the vas deferens.
“Intravas injection of Vasalgel in sexually mature adult male rhesus monkeys was effective in preventing conception in a free-living, group environment,” write VandeVoort and team… “Complications were few and similar to those associated with traditional vasectomy.”
The authors say that now the efficacy of Vasalgel has been proven in monkeys and previously rabbits, researchers are now preparing to test the contraceptive in human trials. The first study will test the contraceptive’s efficacy and subsequent studies will assess the possibility of reversal and restoring sperm flow.
An organization called the Parsemus Foundation (Berkeley, California) aims for Vasalgel to become available and affordable to all men globally via a tiered international pricing structure.