Early results of two Ortho Evra patch safety studies are mixed.(News)

Preliminary results from two large ongoing epidemiologic studies evaluating the safety of the Ortho Evra contraceptive patch provided conflicting data on whether the risk of thrombotic events might be greater with the patch than with oral contraceptive pills.

Last month, the manufacturer, Ortho Women's Health and Urology, announced preliminary results of the two studies, which compare thrombotic event rates in women on Ortho Evra and women on an oral contraceptive pill containing norgestimate with 35 mcg of ethinyl estradiol. One study found the incidence of nonfatal thrombotic events was about the same among users of Ortho Evra and those on the comparator oral contraceptive. But in the second, the incidence of nonfatal thrombotic events was twice as high as among those on the comparator.

These data are preliminary and need to be evaluated further, and are not resulting in any changes to the label or any regulatory actions or specific recommendations on the use of the patch, Dr. Daniel Shames of the Food and Drug Administration emphasized in an FDA-sponsored teleconference, held the day after the manufacturer released these results. The studies are using data from large medical claims insurance databases in the United States; these are the first results to become available. Dr. Shames, director of the division of reproductive and urologic drug products in the FDA's Center for Drug Evaluation and Research, Rockville, Md., said that more precise information could be available by May.

The studies are being done because of the finding, reported last fall, that ethinyl estradiol levels in users of the patch were about 60% higher than women on the oral contraceptive (OC) containing the same amount of ethinyl estradiol (35 mcg), although peak concentrations were 25% lower among patch users. This led to changes in the label to reflect these findings. Because the consequences of these ...