The trusted source for
healthcare information and
What's on the horizon in male contraception?
For 50 years, women have had a reliable form of birth control in the form of the combined oral contraceptive pill. What has emerged in the same time period for men?
While no method has moved from the laboratory bench to the retail shelf, tangible possibilities are coming closer into view, says Elaine Lissner, director of the Male Contraception Information Project based in San Francisco. One such potential method is ultrasound. Scientists at the University of North Carolina at Chapel Hill (UNC-CH) have received a $100,000 grant from the Bill & Melinda Gates Foundation of Seattle to examine it as a long-term, reversible contraceptive.
James Tsuruta, PhD, assistant professor in the Laboratories for Reproductive Biology in UNC-CH's Department of Pediatrics, and Paul Dayton, PhD, associate professor and director of graduate studies in the Department of Biomedical Engineering, jointly housed at UNC-CH and N.C. State University in Raleigh, are conducting the ultrasound research. They are moving forward on findings yielded from research conducted by UNC-CH, Family Health International of Research Triangle Park, NC, and funded by the Stanford, CA-based Parsemus Foundation.
Ultrasound has been previously eyed as a potential contraceptive. The late Mostafa Fahim, PhD, former director of the Center for Reproductive Science and Technology at the University of Missouri Columbia was the first to investigate ultrasound, used by physical therapists to treat injuries. Fahim found that with 10-15 minutes of ultrasound application to the testes, animals from rats to rabbits to monkeys, cats, and dogs would have six months of contraception.1 Fahim also studied use of ultrasound in men in a small study; however, his findings were not advanced until recently. Italian researchers have published research showing ultrasound is an effective contraceptive in male dogs.2
In their pilot study, Tsurata and Dayton attempted to replicate Fahim's findings that ultrasound could deplete the testis of developing sperm cells. The scientists were able to use modern-day, commercially available therapeutic ultrasound instruments to deplete the testis of developing sperm cells. While the duo's research was only short-term studies, Fahim's findings indicate the method can provide six months of contraception.
"Fahim used a custom-built ultrasound apparatus," says Tsurata. "We are using commercially available therapeutic ultrasound instruments, so we will have to conduct our own studies on the duration of the effect."
The two scientists are preparing a manuscript to describe their preliminary studies funded by the Parsemus Foundation. The findings indicate that commercially available therapeutic ultrasound instruments can deplete the testis of developing sperm cells, dropping sperm counts in rats to levels that would cause infertility in men.
In their upcoming studies, the two will focus on determining the minimum effective dose of ultrasound that results in reversible contraception in the rat. Once such a dose is identified, they will begin to test the effect of multiple rounds of using ultrasound, says Tsurata. "We want to be sure that multiple uses of this method do not result in any detrimental, cumulative effects," he says. "By the end of this one-year grant, we should have enough data to determine if it is prudent to pursue the use of ultrasound as a human contraceptive."
RISUG enters U.S. trial
Another potential male contraceptive method, RISUG (Reversible Inhibition of Sperm Under Guidance), might be set for clinical trials in the United States by 2012, says Lissner.
The RISUG method relies on the injection of a polymer gel, composed of powdered styrene maleic anhydride combined with dimethyl sulfoxide, into the vas deferens. The gel coats the inside walls of the vas deferens and kills sperm. If restoration of fertility is desired, the polymer is flushed out of the vas deferens with an injection of dimethyl sulfoxide. RISUG is similar to vasectomy but with one significant advantage: It is reversible.
RISUG's final clinical trial in India is slowly but steadily enrolling men, says Lissner. In early 2010, the Parsemus Foundation licensed the rights to begin developing RISUG for use outside India. With this impetus in place, the goals and timeline for RISUG development in the United States are in place, says Lissner. Final decisions on the manufacturer to make RISUG are being made, with a few months devoted to ensuring that the manufactured material is equivalent to that used in the Indian trial. An abbreviated preclinical efficacy study is eyed for mid-2011. If all goes well with these preliminary steps, within 2012, there could be clinical trials of RISUG for U.S. men.
"We've crossed the line where we've moved from the eternal 5-10 years" for a male method, says Lissner. "When you hear someone say "4-5 years," that is a world of difference; that means something is really happening."