A new warning is being issued over the safety of the birth-control patch after a study found women on the patch are twice as likely to develop serious blood clots as those taking oral contraceptives.

It's the second study in less than two years that found women using the Ortho Evra patch - marketed as Evra in Canada - face increased risks for developing blood clots, and is raising new concerns about the potential dangers of this contraceptive method.

The U.S. Food and Drug Administration announced last Friday that the transdermal birth-control patch will carry an updated label warning women about the potential risks, the second time a warning has been issued for the product.

Health Canada said it is reviewing the information from the new study to determine whether to issue any new warnings or label changes to the Evra patch in Canada.Janssen-Ortho Inc., which manufactures the drug in this country, said it submitted the same clinical evidence to the FDA and Health Canada.

The new study was conducted by the Boston Collaborative Drug Surveillance Program for Johnson & Johnson, parent company of Janssen-Ortho.

It's the latest chapter in the controversial history of the birth-control patch and comes in the wake of reports from Health Canada that two women died and numerous others suffered serious medical problems after using the product.
 

The birth-control patch has been available here since 2004. The risk of blood clots or other serious medical problems for women using the Evra patch is small, Janssen-Ortho said, and could increase if a woman is overweight or smokes.

In 2006, the FDA and Health Canada issued warnings about the potential risks after a study found women on the patch face a higher risk of blood clots than those on the Pill. Another study by different investigators found no increased risk.

But the latest finding seems to confirm fears about the patch and should send a strong message to women that they could be exposed to a potential health threat, said Anne Rochon Ford, co-ordinator of Women and Health Protection, a national advocacy group.

"There were a lot of alarm bells going off for us from the beginning with this patch," she said. "Contraception is used, by and large, by a healthy population and so the bar for its safety should be higher."

Health Canada has received 17 reports since 2004 of women who suffered blood clots and other serious problems after using the patch. The reports included one woman who died of a heart attack and another from blood clots in her lungs.

Janssen-Ortho has defended its product, saying that it is safe when used according to instructions on the label.

Although there has been no conclusive evidence tying the medical problems to the Evra patch, mounting reports of problems combined with new evidence of higher risks should make some women think twice about using the patch, said Madeline Boscoe, executive director of the Canadian Women's Health Network.

Part of the increased risk may result from the fact the patch exposes women to more estrogen than birth-control pills. The FDA revealed in 2005 that women using the patch receive 60 per cent more estrogen.

Although the estrogen levels of the Evra patch sold in Canada are different than its U.S. counterpart, Health Canada said they "deliver a similar amount of estrogen" with the same potential for adverse health effects.

Ms. Boscoe said the Evra patch is a good example of why consumers should steer clear of new drugs in favour of medications that have been on the market for many years. That's because some drugs may have unknown side effects or other potential problems that won't necessarily come to light during limited clinical trials.