AmericaScientists expect a lot from research on the male contraceptive pill, but the works are mostly limited to the laboratory scale.
In a recently published animal study at the University of Minnesota, scientists created a birth control pill for male rats that was 99 percent effective. The drug targets male hormones, specifically a protein involved in sperm production and fertility.
The scientists called the compound YCT529. They gave the mice the drug for four weeks. As a result, their sperm count decreased significantly. 4 to 6 weeks after stopping the pill, fertility returns to normal. This research heats up the race to develop male contraceptives, which began in the 1970s.
There are currently two forms of birth control used by men: condoms and vasectomy. Bobby Najari, assistant professor of urology and director of the Male Infertility Program at New York University Langone Health Medical Center, does not recommend a vasectomy if men still want to have children in the future. . Rehabilitation of fertility after the procedure is often lengthy and not always successful. Vasectomy is also prone to infections, short-term and chronic pain.
Condoms have little long-term health effects, protecting users against sexually transmitted diseases, but they are “unpopular”. Many people who use condoms still have unwanted pregnancies. The percentage of Americans who don’t use condoms is 13%, according to the Centers for Disease Control and Prevention (CDC).
New research from the University of Minnesota is said to be very promising. However, some scientists doubt its feasibility, questioning whether the drug will actually hit the market, or just stay in the lab like its predecessors.
“I will continue to be skeptical until I see data from clinical trials,” said Dr. Amin Herati, director of the male infertility and male health program at the Brady Institute of Urology at Johns Hopkins. He explained that there are many differences between genes in the reproductive system of humans and mice.
Dr. Christina Wang, a specialist in contraceptives at the Lundquist Institute, Harbor-UCLA Medical Center, said: “These are new compounds. You don’t know what they are unless you do toxicological studies. “.
Experts at the University of Minnesota have studied animals, but Wang said human trials are needed to assess the safety of the drug.
However, even if the drug fails in the future, scientists are optimistic because they have discovered a new class of compounds that could become a backup option for other drugs.
Professor Gunda Georg, of the University of Minnesota School of Medicine, who led the study, points out what makes the new drug different from previous products. The compound produced no discernible side effects in rats, even when tested at high doses.
“They eat, drink, have sex even without sperm,” Professor Georg said.
This is not the first study of oral contraceptives with a formula that targets male hormones. In the 1990s, the World Health Organization (WHO) studied testosterone as a potential male contraceptive, finding it highly effective in reducing sperm count. However, the side effects of the drug are weight gain, acne, irritability, mood swings.
Some other drugs show more serious side effects. In 2012, researchers halted a trial of the hormones progestogen and testosterone because men experienced severe acne, depression, and post-injection pain.
Besides the hormone method, scientists are testing a variety of other technologies to create male contraceptives.
Experts in the US and China recently discovered a compound that disables sperm function instead of inhibiting their production. The compound known as triptonide, purified from the Chinese herb Tripterygium Wilfordii Hook F, has been shown to cause infertility.
According to research published in Nature Communications, on March 3, the compound was able to deform and lose sperm function in mice and monkeys. It disrupts the developing function of sperm cells, eventually leading to a defect in the final produced sperm cell.
This effect persisted for many months without harm or side effects in animals. More importantly, when the animals stopped taking the drug, their fertility was restored after several weeks. The properties of triptonide could lay the groundwork for an effective male contraceptive.
The compound has not been tested in humans, but the results of the study are still useful, helping to identify methods that disable rather than completely stop sperm production.
The National Institutes of Health also funded a clinical trial of a hormonal contraceptive gel called NES/T. The gel contains the progestin compound segesterone acetate (brand name Nestorone), which, in combination with testosterone, is easily absorbed through the skin.
Progestin suppresses the natural production of testosterone in the testicles, reducing sperm production to a minimum. Testosterone replacement maintains normal libido and other functions. Men will apply the gel to their shoulders and arms once daily.
The NES/T is in phase two testing. Dr. Wang, also the principal investigator of the work, said the gel could be available in five years.
Researchers in India are testing a non-surgical vasectomy procedure, called RISUG (reverse inhibition of spermatozoa). Accordingly, the doctor will inject a gel into the cavernous bodies in the penis to store sperm.
However, these studies are limited to the laboratory scale. A form of contraception for men as easy as the pill, patch, injection or ring similar to women is still a distant idea.
“I’m excited to see promising results in animal trials. But each time I’m disappointed,” said Professor Bobby Najari.
Thuc Linh (According to NY Times)