Male contraceptive was successfully tested on monkeys

Oleg Lischuk, N+1

American scientists have reported the success of testing the male contraceptive Vasalgel on monkeys. The report on the work is published in the journal Basic and Clinical Andrology (Colagross-Schouten et al., The contraceptive efficacy of intravas injection of Vasalgel™ for adult male rhesus monkeys).

The set of contraceptives available to men is actually reduced to the use of condoms (which provide good, but not absolute protection) or vasectomy – surgical crossing of the vas deferens. Such an intervention leads to the constant inability to have children, but if desired, you can perform an operation to restore the duct (although it is not always successful). Therefore, for several dozen scientists have been looking for a way to provide men with reliable contraception that would be minimally traumatic and easily reversible.

The most promising direction of these searches can be called the use of biocompatible gels that are injected into the vas deferens and reliably block its lumen (another hypothetical mechanism of action is the destruction of sperm membranes under the action of electric charges in gel molecules). If necessary, the gel can be washed out of the duct by solvent injection.

This method of contraception, called RISUG (Reversible inhibition of sperm under guidance, is most often translated into Russian as Reversible Sperm containment under guidance), was developed by Indian researcher Sujoy Guha. His preparation from a styrene copolymer with maleic anhydride is undergoing phase III clinical trials in India. Vasalgel was developed on the basis of this drug by the American non-profit organization Parsemus Foundation. In early preclinical trials on rabbits, he demonstrated one hundred percent effectiveness, as well as the reversibility of the procedure.

At the next stage of testing, employees of the University of California and the Parsemus Foundation injected Vasalgel into 16 adult male rhesus macaques. A week later, they were returned to open enclosures, each of which contained from three to nine females who had previously brought offspring. All males spent at least one mating season with females, seven of them for two years.

During the study, none of the females became pregnant. The only significant complication of the procedure was the incorrect introduction of the gel in one of the males, which led to the formation of granuloma (focal growth of connective tissue in response to chronic inflammation) and required unilateral vasectomy. Gel washing experiments will be carried out in the next phase of testing.

In addition to barrier methods (preventing the penetration of sperm into the female genital tract), pharmacological methods of male contraception with various (hormonal, metabolic and other) mechanisms of action are also being developed. Some of them are undergoing different phases of preclinical and clinical trials, but none has yet been approved for use.

A new direction for such developments is being opened by the recent work of American researchers. They found a mechanism of "switching speeds" in spermatozoa, which is activated by egg progesterone. Drugs that selectively act on this mechanism may turn out to be contraceptives that are effective when taken by both men and women.

Portal "Eternal youth" http://vechnayamolodost.ru  07.02.2017