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By Maggie Fox
National Institutes of Health are looking for some good men to try a new birth control gel for men.
The gel, rubbed daily on the shoulders, gradually reduces the number of sperm, so that men can not put a pregnant woman. The National Institute for Children's Health and Human Development (NICHD), part of the NIH, plans to recruit about 400 couples at sites around the world to test the effectiveness of the gel in preventing pregnancy. as well as appreciation of people if men will use it as directed.
"This is the first time men have used it as a couple to test their effectiveness," said Diana Blithe, head of the NICHD Contraceptive Development Program.
The gel formulation, called NES / T, includes a compound containing a progestin called segesterone acetate, which is manufactured under the brand name Nestorone, with a dose of testosterone.
"It is applied on the back and shoulders and is absorbed by the skin. The progestogen blocks the natural production of testosterone in the testes, reducing sperm production to low or no levels, "NICHD said in a statement.
It is formulated as a gel because Nestorone is not absorbed into the body when taken orally, and testosterone does not remain in the body for a full day when taken in tablet form. Both hormones last longer and work best when administered by the skin.
There is currently no male hormonal contraceptive in commerce in the US market. All men should choose from condoms or vasectomy.
"Worldwide, 85 million pregnancies (or 40% of all pregnancies) per year are unplanned, which contributes to a higher incidence of adverse health effects for women and infants," he said. the Population Council, which developed the product, in a statement.
Nestorone, combined with estradiol, a hormone, is also used as a female contraceptive. A product was approved by the US Food and Drug Administration in August as part of a vaginal ring that women can use as a method of contraception.
How can the same hormone work as a contraceptive for men and women? This is because many common hormones have similar chemical structures, said Blithe.
In humans, the hormone causes the body to think that it can stop producing sperm. In women, it mimics pregnancy and causes the body to think that it can stop making eggs. "The male normally has very low levels of progesterone. Now, they are exposed to a high amount, and this tells the testicles: "Oh, there are a lot of steroids in the world, so I do not need to make any more now," he said. Blithe.
Restoring testosterone at the same time as Nestorone prevents unwanted side effects such as decreased libido and muscle wasting, said Blithe.
One question is how effective will the treatment be? Different methods of birth control have different efficiencies.
"If we talk about a daily pill in women, if they use it to perfection, the failure rate is extremely low," Blithe said. "In typical use, the failure rate is 7%. With condoms, if they are used to perfection, the failure rate is low but, in general, it is 12%. "
In theory, men might forget to use the gel for a day without consequences. "If they stop using it for three, four or five days, it will not work as expected," Blithe said.
"Do I think they're going to use it? Certainly they are able to use it and they are willing to use it. But people are human and people forget about it. .