Condoms or condoms have existed for around 2,000 years and are, together with vasectomy, the only methods of male contraception. However, they could soon have a competitor, since a group of scientists from Weill Cornell Medicine has developed a male contraceptive pill that can paralyze sperm for up to two and a half hours, as shown in a preclinical study carried out with mice.
This experimental drug could become a tailored male contraceptive if the study results published in Nature Communications are confirmed in a human clinical trial, thus constituting a “game changer” for contraception, the co-lead authors have stated. of the study, Dr. Jochen Buck and Dr. Lonny Levin, professors of pharmacology at Weill Cornell Medicine.
Men could take this pill before having sexual intercourse and regain fertility afterwards. Male oral contraceptives represent a challenge for science because men are not exposed to the risks associated with pregnancy and for this reason they are considered to have less tolerance to the possible side effects of a medication of these characteristics.
With a single dose of the compound, the spermatozoa of the mice remained immobile for up to two and a half hours, and at 24 hours almost all had recovered normal movement.
The Drs. Buck and Levin discovered that soluble inhibitors of an enzyme called adenylyl cyclase (sAC) can decrease sperm motility in mice and humans. This enzyme is key to activating the movement and maturation capacity of spermatozoa so that they can move through the female reproductive tract and fertilize an egg. They also found that mice genetically modified to lack sAC are infertile.
Paralyze sperm to cause temporary infertility
The researchers developed a compound called TDI-11816 that inactivates the sAC enzyme and, when injected into mice, prevented the sperm they produced from propelling forward or maturing. The compound did not affect the sexual behavior of the rodents, but it eliminated fertility in the hours following its administration.
With a single dose of the compound the spermatozoa of the mice remained immobile for up to two and a half hours and the effects lasted in the reproductive tract of the females after mating. After three hours, some sperm began to recover motility, and after 24 hours almost all had recovered normal movement. Contraceptive efficacy was 100% in the first two hours and 91% in the first three hours.
In addition, when this drug was administered continuously for six weeks, no adverse effects were observed and, although in most cases it was injected, the researchers found that when administered orally the sperm motility of the mice decreased to similar levels.
“Our inhibitor works in 30 minutes to an hour,” explained Dr. Melanie Balbach, a postdoctoral associate in the Buck and Levine lab. “All other experimental hormonal or non-hormonal male contraceptives take weeks to reduce sperm counts or render them unable to fertilize eggs.”
A contraceptive that would allow men to control their fertility
The researcher has also highlighted that it takes weeks to reverse the effects of other hormonal and non-hormonal male contraceptives in development, while sAC inhibitors wear off in a matter of hours and men would only need to take them before sexual contact to avoid unintended pregnancy. desired, which would allow them to control their fertility.
Luz Candenas de Luján, senior scientist at the CSIC and researcher in reproductive biology at the Institute for Chemical Research CSIC-University of Seville believes that these researchers “have hit the key” because “the drug targets a very specific enzyme of sperm (one of the isoforms, ADCY10, is expressed almost exclusively in these cells)”, according to what he declared to SMC Spain.
The expert adds that “although this research has been carried out in mice and clinical trials are necessary to corroborate the efficacy of the drug in humans, this study opens the door to the development of the first single-use male contraceptive pill, offering an interesting alternative to the exclusive use of oral contraceptives in women”.
“The team is already working to make sAC inhibitors more suitable for use in humans,” Dr. Levin noted. The team’s next objective is to repeat the tests in another animal model, and they hope that the results of the tests will be used to carry out clinical trials in humans in which the effects of sAC inhibition on sperm motility in healthy men would be verified. concludes Dr. Buck.
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