Birth Control Patch Might Raise Clotting Risk More Than Pill

Women using the increasingly popular birth control patch may face double the risk of blood clots compared with women taking contraceptive pills, but more investigation is needed to see whether the preliminary findings are valid, federal regulators said Friday.

“We’re not sure what this means clinically, but it’s information that people need to know about,” said Dr. Daniel Shames, who heads the Food and Drug Administration division that evaluates contraceptives.

“At this time, we do not plan on taking any specific regulatory action based on these preliminary results,” he said.

Blood clots usually form in the legs, and sometimes in the lungs. They can travel to the heart or the brain, causing heart attacks and strokes. Women taking a hormonal contraceptive are at elevated risk of clotting, although incidents are uncommon: Each year, about three to five such women in 10,000 develop a clot.

Manufacturer Ortho-McNeil Pharmaceutical Inc. said it was cooperating with the FDA in the ongoing scientific investigation. Sales of the patch totaled more than $400 million in 2004, according to DrugTopics.com, an industry website. Johnson & Johnson, of which Ortho-McNeil is a division, sponsored the research that is raising concern.

Marketed as Ortho Evra, the birth control patch has been used by more than 4 million women since it was approved by the FDA in late 2001. It releases estrogen directly into the bloodstream through vessels near the surface of the skin. One patch can be worn for seven days; the pill must be taken daily.

The patch exposes women to 60% more estrogen than a typical birth control pill, according to the FDA.

“Because it is absorbed directly through the blood as opposed to a pill taken by mouth ... the total exposure is more,” Shames said.

The FDA issued a warning in November about the higher levels of estrogen with the patch.

Two recent studies commissioned by Johnson & Johnson produced seemingly contradictory results.

A recently published study by the Boston Collaborative Drug Surveillance Program found no higher risk of blood clots among patch users than among women taking standard birth control pills.

But preliminary findings from a study by i3 Drug Safety found twice the risk of leg and lung blood clots for patch users compared with pill users. Complete data from the second study have not been publicly released.

Both studies used insurance claims data to track tens of thousands of pill and patch users. Researchers are also investigating whether patch users are at higher risk of heart attacks and strokes, although preliminary data suggest that they are not, the manufacturer said. FDA officials said long-term studies might be needed to measure the risk.

Last year, an Associated Press analysis of FDA reports of serious drug side effects indicated that patch users’ rate of death and blood clots was triple that of pill users.

Some critics of the FDA say the risk should have been clear in clinical trials before the patch was approved.

“It is no more effective than the pill and has a higher risk, because it delivers significantly more estrogen,” said Dr. Sidney Wolfe of the advocacy group Public Citizen.

The FDA’s Shames said that before the drug was approved, it was tested on 2,000 to 3,000 women, and two suffered serious blood clots. One patient had undergone surgery, he said, so it was unclear whether her problem was related to the patch. (Surgery elevates the risk of clots.)

“Statistically, it had no meaning,” Shames said.

But Associated Press reported last year that those cases had alarmed an FDA drug reviewer, who recommended that patients and doctors be clearly advised of the risk and that follow-up studies be conducted.

Susan Wood, a former head of the FDA women’s health office, said the agency “still doesn’t have enough data to make a call” on the safety of the patch.

Wood said women using the patch should weigh the new information against their individual circumstances, including their health and how they use birth control. Wood resigned from the agency last year to protest delays in approving the “morning after” contraceptive for sale without a prescription.

“Women should be aware that [the patch] does have a higher estrogen level, and this potentially can lead to greater side effects,” she said. “But the increase in risk, even if real, would still be fairly low. This is more information that is helpful, but it is not something that should send women off their birth control method.”