Two hundred years is a long time, particularly in the world of medicine. But when it comes to new, non-permanent birth control methods for men, it’s as if time has stood still. For two centuries, only one such method has come along: the condom.
For men like Dan Schumpert, that’s a problem. The 25-year-old Schumpert, who lives in Federal Way, Wash., with his wife, Alana, and their two young children, says, “I’d tried the condom, and it just … bothered both of us.” But like many men, he also wants to be more involved in birth control, not leaving it entirely up to the woman. “I’m a firm believer that birth control is not the woman’s full responsibility,” he declares.
But aside from the condom, Schumpert had few options for putting this belief into practice without risking an unwanted pregnancy. One option is a vasectomy—a generally irreversible surgical procedure that keeps sperm from entering seminal fluid. But that alternative was out; the couple plans to have more children.
This left little choice. Dan’s beliefs aside, Alana Schumpert, like millions of other women, had to bear most of the burden for birth control.
Enter researchers at the University of Washington. In an unusual project—the only field trial of its kind in the nation—UW professors are testing an injectable contraceptive that gives men the same kind of contraceptive freedom—and responsibility—now generally available only to women who use “the pill.”
So far, the project appears promising, researchers report. If an injectable male contraceptive can be adapted for widespread use, it could become the first new, non-permanent method of male birth control since the condom.
The project’s goal, according to Dr. C. Alvin Paulsen, UW professor of medicine, is to find a “safe, reversible and reasonably effective “method for male birth control that offers an alternative to condoms and vasectomies. He defines “reasonably effective” as a method that approaches the condom failure rate, estimated at between 5 and 17 percent.
The UW is one of nine institutions worldwide working on male birth control through sperm reduction techniques, Paulsen says. The research is sponsored by the World Health Organization and other groups, including—in the United States—the National Institutes of Health and the U. S. State Department.
In the latest phase of Paulsen’s study, researchers have been conducting clinical trials using weekly injections of the synthetic hormone testosterone enanthate (TE) to induce zero sperm production in 60 to 70 percent of normal adult males.
“The concept we’re testing is whether a laboratory diagnosis of zero, or close to zero, sperm production results in a zero, or near zero, fertility rate,” Paulsen explains.
For volunteers, the project begins with a brief control period. Once the injections start , the researchers monitor sperm production until it reaches zero. If the count hits bottom and stays there, the couple begins a year-long period where all forms of contraception are dropped except the weekly injections. When the year is over, the injections stop and the volunteers are followed until full recovery occurs.
As of this past summer, 20 men in the study—including Dan Schumpert—had at least six months of exposure to the synthetic testosterone, Paulsen explains. Thirteen of them achieved the target of zero sperm count, and of this group, seven have completed the yearlong phase free of other contraceptives. The remaining men failed to reach the zero production target. Out of those subjects, five have recovered normal sperm production thus far. There were no pregnancies among the 20 couples involved.
The other five male partners among the original 25 couples have had less than six months of exposure to the synthetic testosterone, Paulsen explains. Four of these men are still in the study, but one couple had an unplanned pregnancy when a condom failed two months after the man started receiving his injections. At that point his sperm count had not yet dropped below normal levels.
“It’s not too surprising that a pregnancy occurred during the induction phase, before a volunteer shows a sharp drop in sperm production,” Paulsen says. “The fact is, some pregnancies also occur when people use diaphragms and condoms.”
Although most of the original 25 couples responded to newspaper ads seeking volunteers for the study, Planned Parenthood referred the Schumperts to Paulsen. Before being accepted for the study, the men received a physical examination that included collection of blood, urine and seminal fluid; and verification that both partners in each couple were “reproductively normal.” The women were required to provide evidence that they ovulate normally and were not pregnant.
“We’re encouraged that no one has dropped out of the program for medical reasons,” Paulsen says. In contrast, about 25 percent of women who try birth control pills and other female methods abandon the method by the end of the first year, he notes.
During the induction period, Schumpert and other male subjects had monthly checkups with a physician to detect changes in blood pressure and any evidence of kidney or liver damage. No changes were observed. Cholesterol also was checked, and other than a lowering of high-density lipoproteins that Paulsen characterizes as “slight,” no effects were observed. He adds that it is not yet clear what additional risk, if any, this would pose to someone taking the synthetic hormone for contraception over an extended period.
No behavior al changes were observed, Paulsen notes, but some men in the study tended to gain a few pounds. Weight gain is not an unusual side effect of testosterone use, he explains. Also, some men who had acne during puberty experienced a recurrence of the skin condition when they began receiving the injections.
The synthetic hormone testosterone enanthate is commonly given to men who do not produce normal amounts of their own hormone, Paulsen explains. In the study, 200 milligrams were administered weekly. While testosterone enanthate is an anabolic steroid, the contraceptive dosage is well below levels that some athletes use, he adds. Moreover, different anabolic agents are used by such athletes and can damage the liver.
Synthetic testosterone also has been used to treat male infertility since about 1950, according to Paulsen. In patients with a low sperm count, supplemental dosages of testosterone are used to temporarily shut off sperm production.
When the testosterone is withdrawn, about a fifth of these couples achieve a pregnancy due to improvement in the husband’s semen. There are no published reports of testosterone synthetic hormones—alone or combined—having induced a permanent reduction in sperm count, he adds.
The synthetic testosterone used in the study was donated by E. R. Squibb & Sons, Inc. Paulsen estimated the current retail cost of injections at about $10 per shot.
“So far, we’ve been testing the concept, and the results are promising,” Paulsen said. But obviously, most men would find a weekly injection impractical, and improved delivery methods have to be found before the concept can take hold on a large scale.”
Such methods could include biodegradable hormone pellets placed under the skin that last for several months, he added, or some other time-release mechanism.
Paulsen said the study so far has demonstrated that some men respond to the drug faster than others. “But we don’t know why some men fully respond (to the hormone) and others do not,” he comments. He said he and his colleagues—including Dr. William J. Bremner, UW professor of medicine and chief of medical service at the Seattle Veterans Administration Medical Center, and Dr. Alvin Matsumoto, UW assistant professor of medicine—hope to examine this question in the future using other hormonal methods.
“We also need to define that level of sperm production that will still be associated with effective contraception for men who do not become azoospermic (achieve a zero sperm count),” Paulsen says. “Our expectation is that if members of this group stay at very low levels for a year, they won’t experience a failure rate that exceeds conservative estimates of the condom failure rate,” he adds.
To this end, the next phase of Paulsen’s research—starting next year—will examine whether the injectable testosterone is effective in preventing pregnancies if the male has a very low, as opposed to zero, sperm count (less than 5 million per milliliter). Men who reach this level are generally considered infertile, Paulsen notes.
Schumpert had his last injection in July. “I hated to see it end,” he says, despite having to overcome a childhood fear of needles. “For us, it was a great thing. It took all the worry out of pregnancy and really improved our sex life.
“I’d gladly do it all over again—and pay for it, if necessary,” he adds. “It’s about time something came along other than condoms for men.”