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Male contraceptives: Research examines options
When you review birth control options with your female patients, you tick off several items: a shot, a patch, an intravaginal ring, intra-uterine devices, barrier methods, and several types of pills. But when it comes to meeting men’s reproductive health needs, your list is considerably shorter.
Male contraceptive methods account for almost one-third of all current contraception in the United States, despite having just two effective options: condoms and vasectomy.1
"Increasing the number of male contraceptive options available will help make men equal partners in family planning, provide additional options for women who are unable to use birth control, and provide more options for population control in a hazardously growing global population," says John Amory, MD, assistant professor of medicine at the University of Washington in Seattle. Amory recently presented an update on the status of male contraceptives at the annual meeting of the Washington, DC-based Association of Reproductive Health Professionals, held in La Jolla, CA.2
While researchers have explored several avenues of contraception for men, moving closer to an actual product has been difficult with no backing from a major pharmaceutical company, ge observes.
This scenario is set to change, however; Organon International of Oss, the Netherlands, and Schering AG of Berlin, Germany, are co-sponsoring a Phase III clinical trial of 250 men at 14 sites: the University of Washington; the University of California, Los Angeles; and 12 European sites. The study will look at the use of an etonogestrel implant used with injections of testosterone undecanoate, says Amory.
The etonogestrel implant is designed to suppress sperm production in the testes; however, its use can lead to a drop in testosterone concentrations in the blood. To prevent side effects such as loss of libido, researchers have looked at giving testosterone injections. Previously available testosterone preparations required frequent administration; with the long-acting formulation of testosterone undecanoate, researchers may be able to see steady-state drug levels in the bloodstream and a user-friendlier rate of administration.3
The study’s design calls for seven different treatment groups, with the injection intervals ranging from six to 12 weeks, with the average injection interval at two months, says Amory. If the results prove promising, research may yield a product in three to four years, he states.
Where’s a male pill?
A 2000 survey designed to gauge perceptions of proposed hormonal methods indicate that men are most interested in a contraceptive pill.4 The Population Council, a New York City-based research organization, is looking at analogs of lonidamine, an anti-cancer drug.5
Researchers have noted one side effect of lonidamine is a temporary, profound disruption of spermatogenesis; however, due to other toxic side effects, lonidamine cannot be used as a contraceptive.4 Scientists have since developed two analogs of lonidamine that may help disrupt the process that is essential to the formation and development of sperm.6
"We are testing both of those compounds in animals at the moment," says Regine Sitruk-Ware, MD, the council’s executive director of contraceptive development. "It is very effective and reversible. It is effective when given once a week, so it could also be a more convenient way of administration."
Researchers must complete a full toxicology program before starting any clinical study of the compounds, she notes.
MENT for men?
The Population Council continues to research the potential male contraceptive use of its trademarked synthetic androgen, 7alpha-methyl-19-nortestosterone (MENT). Scientists are studying use of the androgen since it suppresses gonadotropin secretion, which leads to suppression of testosterone and sperm production in the testes.
Research suggests that MENT acetate implants are a promising method for long-term androgen administration in male contraception.7,8 Sitruk-Ware says MENT has an advantage over other testosterone derivatives in that it does not impact the prostate. Further tests are needed to prove its safety and efficacy as a contraceptive.
"It is very well accepted," she notes. "The men who have participated in the studies were very keen to continue the method."
1. Alan Guttmacher Institute. Facts In Brief. Contraceptive Use. New York City; accessed at www.agi-usa.org/pubs/fb_contr_use.html.
2. Amory JK. Male contraception: Update 2003. Presented at the 40th annual clinical conference of the Association of Repro-ductive Health Professionals. La Jolla, CA; September 2003.
3. Schwartz JL, Gabelnick HL. Current contraceptive research. Perspect Sex Reprod Health 2002; 34:310-316.
4. Martin CW, Anderson RA, Cheng L, et al. Potential impact of hormonal male contraception: Cross-cultural implications for development of novel preparations. Hum Reprod 2000; 15:637-645.
5. No author listed. Altering cell bonds in testis may yield contraceptive. Pop Briefs 2002; 8:4.
6. Cheng CY, Mo M, Grima J, et al. Indazole carboxylic acids in male contraception. Contraception 2002; 65:265-268.
7. Suvisaari J, Moo-Young A, Juhakoski A, et al. Pharmacokinetics of 7 alpha-methyl-19-nortestosterone (MENT) delivery using subdermal implants in healthy men. Contra-ception 1999; 60:299-303.
8. Von Eckardstein S, Noe G, Brache V, et al. A clinical trial of 7alpha-methyl-19-nortestosterone implants for possible use as a long-acting contraceptive for men. J Clin Endocrinol Metab 2003; 88:5,232-5,239.