Science investigates contraceptive gels

When discussing spermicides with prospective users, family planning providers in the United States have only nonoxynol-9 (N-9) formulations in the contraception arsenal. What if there were other formulations added to the mix?

Scientists are looking at two candidates, Usher-cell (cellulose sulfate) and BufferGel, as two possible spermicidal gels. In addition, both potential products are being eyed for their protection against sexually transmitted diseases (STDs), including HIV.

Research findings presented at the recent American College of Obstetricians and Gynecologists annual meeting in Washington, DC, indicate that Ushercell appears to be as effective as non-oxynol-9 in a Phase II noncomparative contraceptive effectiveness trial of 200 couples using the gel as their primary contraceptive for six months.1 Ushercell is under development by Polydex Pharmaceuticals Limited in Toronto, with collaborative support from the CONRAD (Contraceptive Research and Development) program in Arlington, VA.

At the recent Microbicides 2006 meeting in Cape Town, South Africa, results were reported from two pivotal contraceptive efficacy trials of BufferGel.2 According to Thomas Moench, MD, president of Baltimore-based ReProtect, which is developing the potential product, one trial compared the contraceptive efficacy of BufferGel used with a diaphragm to the contraceptive efficacy of a currently available spermicide used with a diaphragm. The BufferGel/ diaphragm combination was proven noninferior to the spermicide/diaphragm, he reports. The second open-label trial of BufferGel used with a diaphragm confirmed its contraceptive efficacy, he states.

"ReProtect will be preparing a New Drug Application seeking approval of BufferGel as an over-the-counter spermicide for use with a diaphragm for contraception," Moench says.

Look for alternatives

Family planning providers have counseled patients not to rely on N-9 spermicides as a means of HIV prevention since research appeared in 2000 regarding the ineffectiveness of the spermicide.1 Further caution came after 2002, when study findings indicated that N-9 fails to protect against such STDs as urogenital gonorrhea and chlamydia.2

Sexually active women should consider their individual HIV/STD infection risk when choosing a method of contraception; family planning providers should inform women at risk for HIV/STDs that N-9 contraceptives do not protect against these infections.3

Research updates presented at the Microbicides 2006 conference focused on the use of Ushercell in the prevention of HIV and other sexually transmitted infections.4,5 Enrollment is under way in two multi-country Phase III clinical trials to test the potential product's effectiveness in preventing HIV/AIDS transmission, researchers report.

Scientists also are examining use of BufferGel in a single-size, inexpensive, diaphragm-like device.6 The device, BufferGel Duet, is designed to function as a cervical barrier and applicator for the spermicide/microbicide, and it is intended for contraception and prevention of disease, says Moench.

The Duet's dome is designed to deliver BufferGel on its vaginal lumen and its cervical sides, explains Moench. The dome folds to prevent the gel from being wiped off during insertion, but then it opens to distribute gel widely within the vagina, says Moench.

"Efficient delivery on the vaginal lumen side is particularly important and appropriate for its intended disease prevention function," states Moench. "Thus, Duet is designed to protect not only the cervix, but also the vaginal epithelium."

The Duet is being developed with an eye toward it being first provided in a reusable version loaded by the user with pre-measured sachets of gel, says Moench. Another format, a pre-loaded, disposable version, also may be offered in the future for additional convenience.

What are the advantages of using a spermicide or microbicide gel in combination with the Duet over using the gel alone? According to Moench, potential advantages include an expected increased efficacy from the physical cervical barrier, and provision of a reusable vaginal applicator at minimal cost. The Duet's theoretical advantages over a conventional diaphragm include efficient gel delivery on both sides, a "one-size-fits-all" approach with no need for fitting, and easier use, notes Moench.

References

  1. Mauck CK , Frezieres RG, Walsh TL, et al. Noncomparative contraceptive effectiveness trial of cellulose sulfate gel. Obstet Gynecol 2006; 107:14S.
  2. Barnhart KT. BufferGel with diaphragm found to be an effective contraceptive in two Phase II/III trials. Presented at the Microbicides 2006 Conference, Cape Town, South Africa; April 2006.
  3. Centers for Disease Control and Prevention. Nonoxynol-9 spermicide contraception use — United States, 1999. JAMA 2002; 287:2,938-2,939.
  4. Van Damme L, Ramjee G, Alary M, et al. Effectiveness of COL-1492, a nonoxynol-9 vaginal gel, on HIV-1 transmission in female sex workers: A randomised controlled trial. Lancet 2002; 360:971-977.
  5. Roddy RE, Zekeng L, Ryan KA, et al. Effect of nonoxynol-9 gel on urogenital gonorrhea and chlamydial infection. JAMA 2002; 287:1,117-1,122.
  6. Ballagh SA. BufferGel Duet: Safety and acceptability study of a novel product combining a mechanical and chemical barrier in the vagina. Presented at the Microbicides 2006 Conference. Cape Town, South Africa; April 2006.