Avanti: Similar efficacy to latex, more breaks
Results from a recent clinical efficacy study show the Avanti polyurethane condom compares well with a latex condom in terms of pregnancy prevention but falls short when it comes to product performance.1
Even though manufacturer London Interna-tional Group (LIG) voluntarily moved to increase the thickness of its polyurethane condom by 15% to 20%, the Avanti recorded a breakage and slippage rate of 8.5% more than five times the 1.6% rate reported for the control latex condom. This new finding confirms initial research that showed a thinner version of the current condom broke or fell off at a rate of 10.8% during intercourse or withdrawal, compared with a 1.7% rate for the same control condom.2 Both studies were commissioned by the National Institute of Child Health and Human Development (NICHD) in Bethesda, MD.
The new study was a randomized, controlled, double-masked trial of some 800 couples. In 1,804 uses, the Avanti broke 66 times during intercourse and six times during withdrawal. In comparison, the Ramses Sensitol control latex condom broke just seven times during sex, and once during withdrawal, during 1,882 uses. Both products are manufactured by LIG.
William Potter, PhD, LIG group scientific affairs director, says the company believes that the new breakage rate "compares favorably with latex condoms in similar populations and similar sizes of studies." When questioned about the breakage/slippage rates between the polyure-thane and latex condoms used in the study, Potter points out that the control latex condom exhibited a very low breakage rate. The Avanti condom, he says, "has a very good breakage rate compared to latex condoms in general. It’s the first of a new generation of condoms. And obviously, as we put the same effort into Avanti that we put into latex, I have absolutely no doubt that we will actually find similar, if not better, breakage rates in the future. We’re basically looking at comparing new technology against well-established technology."
Take a closer look at the efficacy rates
The efficacy study, conducted by the Los Angeles Regional Family Planning Council, calculated both six-month typical-use and six-cycle consistent-use pregnancy rates through the use of life-table analysis. The clinical trial design also included a nested breakage, slippage, and acceptability study, which yielded the new breakage information on the two LIG condoms.
Researchers developed efficacy rates that were adjusted for the use of emergency contraception (EC), establishing what is believed to be the first EC use in such a study. Nineteen couples recorded 22 uses of EC with the Avanti; eight couples noted nine uses of EC with the latex condom.
The uncorrected six-month typical-use pregnancy rate for the Avanti was 4.6, compared with 6.1 for the latex condom. After correcting for EC use, the rate was 5.3 for the Avanti and 6.5 for the latex condom.
In looking at six-month consistent-use pregnancy rates, the uncorrected rate for the poly-urethane condom was measured at 2.6; 1 for the latex condom. When adjusted for EC use, the rate rose to 3.1 for the Avanti and 1.2 for the latex condom.
Although the pregnancy rate for Avanti was not statistically different from the control latex condom, researchers note that the rate could have been influenced by more couples dropping out of the study due to problems with the polyurethane condom. Of the 61 couples who were assigned to Avanti and then withdrew within 60 days of enrollment, 33% had reported one or more condom failures. A total of 36 couples assigned to the latex condom dropped out within 60 days, with only 3% reporting condom failure.
While the study’s findings are not yet published, Contraceptive Technology Update obtained a copy of the final report from NICHD. Results also have been passed to the U.S. Food and Drug Administration (FDA), which approved the Avanti condom in 1991. FDA spokeswoman Sharon Snider declined to comment on the study because the agency is evaluating its results.
The Avanti condom entered a limited number of U.S. test markets in late fall of 1994. Until LIG broadens its original application to the FDA, the only proven benefit recognized by the federal agency is its safety for latex-sensitive couples. With the new efficacy information in tow, however, LIG is moving to expand Avanti’s labeling claims to seek a broader U.S. market, Potter confirms. The company also plans to begin marketing the polyurethane condom in England this fall.
References
1. Nelson A, Bernstein GS, Frezieres R, et al. Study of the Efficacy, Acceptability, and Safety of a Non-latex (Polyurethane) Male Condom. NIH Contract No. 1-HD-1-3109. Bethesda, MD: National Institute of Child Health and Human Development; April 1, 1991-March 31, 1997.
2. Nelson A, Frezieres R, Walsh T, et al. Controlled, Randomized Evaluation of a Commercially Available Polyurethane and Latex Condom (AvantiTM vs. Ramses Sensitol.) NIH Contract No. 1-HD-1-3109. Bethesda, MD: National Institute of Child Health and Human Development; Nov. 6, 1996.