(CBS News) A promising new male contraceptive gel may be an alternative method of birth control for couples, researchers announced this week.
"Up until now, the responsibility for contraception has traditionally always been with the female," study researcher Dr. Christina Wang, a lead investigator at Los Angeles Biomedical Research Institute at UCLA Medical Center, said in a press release. "With these new contraceptive methods for males, the responsibility will be shared. While this gel has great potential and minimal side effects, it does warrant further study as a male contraceptive."
The new gel contains the male hormone testosterone and a progestin called Nesterone. Progestin is a synthetic hormone that mimics the female hormone progesterone and has been found to increase the contraceptive effectiveness of testosterone in men.
The study, funded by the National Institutes of Child Health and Human Development, involved 99 men. One-third of them were given a gel containing testosterone and a placebo for six months, while the remaining two-thirds were given a gel with testosterone and either 8 or 12 milligrams of Nestosterone. Only 56 men completed at least 20 weeks of the treatment protocol.
The researchers found that of men receiving the new gel, 88 to 89 percent achieved a sperm concentration of less than 1 million sperm per milliliter, while only 23 percent of men in the testosterone/placebo group reached that level. Depending on dosage, there was a complete absence of sperm in 69 to 79 percent of the men taking the new gel, compared with 23 percent of the men in the comparison group.
Compared with other male contraceptives, Nestorone didn't cause androgenic side effects such as acne and changes in cholesterol. The study was presented at the Endocrine Society Meeting & Expo this week in Houston and findings are considered preliminary.
"This is the first time that testosterone and Nestorone have been applied to the skin together to deliver adequate amounts of hormones that suppress sperm production," Wang said in a society news release. "Men can use transdermal gels at home - unlike the usual injections and implants, which must be given in a health care provider's office."