The research is in the early days, but Chinese scientists say they use bartending tricks to encourage a new, reversible contraceptive man.
In experiments with rats, the method successfully retained sexually active men from impregnating women for more than two months.
"The two most accessible male contraceptives are condom and vasectomy," said a team led by Xiaolei Wang of Nanchang University. "Reliable and reversible medium-term plan [2 to 20 weeks] the method of contraception between a single condom and permanent contraception is urgently needed. "
Their potential solution was inspired by the colorful layered cocktails often invented by bartenders. In these mixtures, liquids form different layers in a cup. But when mixed or heated, the layers are combined into equal fluid.
Promising, but a long way
So the Wang Group developed a form of male contraception in which layers of materials are injected into vas deferens – the channel through which sperm travels from the testicle to the urethra – to block it.
The block continues until the heat is applied to the blocked surface, causes the layers to mix, break them, and thus exclude vacuums.
The Chinese group said they tested this method in male rats by inserting four layers of materials into vas deferens. In sequence, the injected layers were: a hydrogel representing a physical barrier to sperm; gold nanoparticles that are heated when irradiated with infrared light; ethylenediaminetetraacetic acid (EDTA), a chemical that breaks down the hydrogel and also destroys the sperm; and another layer of nanoparticles of gold.
While in progress, liquid layers in vas deferens prevent male rats from impregnating women for more than 2 months, Wang's team announced Jan. 30 in the magazine ACS Nano.
But when the researchers spotted the nearby infrared lamp of male rats for several minutes, the layers intermixed and dissolved, and male rats were once again able to impregnate women. This offers an "effective and reversible way to fill the gap of the current medium-term contraception strategy" for men, the team said.
But, "although our method promises, there is still a long way to go for practical practice," the Chinese team said. "More animal experiments are needed to confirm the safety of the materials," they say, and the results in animals often fail to fail in humans.
A fertility expert in the United States has agreed that much more studies are needed.
"This study is a very preliminary overview of injected male contraception," said Dr Maria Raush, from Northwest Health Travel in Manhattan, New York. "Although this has a long way to go before it is ready for trial or, of course, to be used in humans, it would be a medical discovery, if it was achieved.