It seems that every few months, the male birth control pill is just around the corner.
This month, a new drug from London touted as the next big prospect for the male birth control pill created a buzz.
The quest for the male pill is, in many ways, the search for the holy grail of contraception. More and more people are clamoring for options that would allow men to share in the burden of preventing pregnancy.
A 2005 study showed that nearly 50 percent of men in the United States would be willing to try a new form of birth control, and up to 72 percent of men in other countries are interested in new forms of male contraception.
In reality, however, researchers are approaching male contraception from multiple angles, many of which are closer to reality than the male pill. After all, the British research is still being performed on tissue in petri dishes -- not in animals or humans.
Condoms are extremely effective at stopping the spread of HIV and other sexually transmitted diseases. But though condoms are up to 98 percent effective at preventing pregnancy when used perfectly, "typical" condom use has fail rates as high as 15 percent.
And vasectomy, in which surgeons cut the tube called the vas deferens that propels sperm out of the penis, is usually irreversible.
So why don't we have a male birth control pill?
"Certainly, contraception has commonly been the responsibility of the woman in the past," says Dr. Peter Schlegel, Professor and Chairman of Urology at the New York-Presbyterian Hospital/ Weill Cornell Medical Center in New York. "But there's no reason that couldn't change."
Standing in the way, however, are many factors that make it difficult to produce male contraception.
"Stopping all sperm production or disabling all sperm is a real challenge, when you're making [millions of] sperm a day," Schlegel says.
"Male physiology is a lot more complicated than female physiology," says Daulat Tulsiani, a professor of obstetrics and gynecology at Vanderbilt University in Nashville, Tenn. "Initially, [it was] thought there was one molecule on the egg and on the sperm that played a role in their interaction."
His research has shown, though, that multiple molecules, especially on sperm, play a role in fertilization.
Further confounding the potential success of the male pill is the "macho" factor.
"If there is any impression that [a form of contraception] changes sex, men won't like it," says Dr. Paul Turek, professor of urology and director of the Male Reproductive Laboratory at the University of California in San Francisco. "We live in a culture of virility."
"Hormonal approaches are the most extensive non-barrier method [studied]," Schlegel says. He says most trials suggest these hormone treatments are inching closer to reality.
These drugs, similar to birth control pills in women, would regulate hormones in the body to decrease sperm production. So far, researchers around the world have conducted extensive human trials.
Yet, most estimates are that a workable drug is still five to 10 years away.
Perhaps closer to market is a device known as the IVD, or Intra Vas Device. The IVD is a double silicone plug designed to block the vas deferens. Researchers believe the result would be similar to that of a vasectomy.
The device is at least "four years away," says Elaine Lissner, director of the Male Contraception Information Project in San Francisco. But she also says, "a lot is going to depend on public pressure and public input" for funding.
The psychological benefit of this device, of course, is that there is no cutting of the vas deferens. This implies that fertility may be reversible, though so far this reversibility has only been proven in monkeys.
Another potential method is Reversible Inhibition of Sperm Under Guidance, or RISUG. In this treatment, doctors inject a chemical into the vas deferens that kills any sperm it touches.
As for the male pill possibility touted in London this week, the advantage of this drug, if it works, is that it would offer an oral pill that would cause only temporary infertility, unlike a vasectomy.
"The time to efficacy [of the drug] is four to six hours, and [it] will wash out within 12 to 24 hours, so this is something that can be used in the short term," notes Dr. Nnaemeka Amobi, professor at King's College in London and head researcher of the drug.
Research is also being done at the cell level, looking at sperm and egg interactions, such as in Tulsiani's work. Some are also looking at ways to develop antibodies against sperm, which may affect how sperm function, or how they fertilize the egg.
"Historically, often studies are started, but when it gets to the expensive stage of testing in men, the money isn't there," Lissner says. "The best methods for men will be long-acting and cheap. The best methods for pharmaceuticals are short-acting and expensive."
More international cooperation is needed as well to bring international devices to the United States, "starting with re-funding the World Health Organization's Male Task Force," Lissner says.
"In general, I think that the development of any new contraceptive option is great news," says Dr. Donnica Moore, president of the Sapphire Women's Health Group. "It gives women and men one more choice to facilitate family planning and reduce the incidence of unintended pregnancy.
"I hope a male pill does make it to market soon," she says.
Yet, until more funding is directed to some very promising options, many researchers say the development of a new form of male contraception is years away.