Health Canada said it will issue a new alert about the painkiller Bextra as regulators in the U.S. said they were strengthening warnings about the drug.

Bextra belongs to a class of drugs called COX-2 selective non-steroidal anti-inflammatory drugs. It is used to treat arthritis and menstrual pain.

Bextra is often used to relieve arthritis pain
Bextra is often used to relieve arthritis pain

The U.S. Food and Drug Administration's new warning label alerts patients to possible heart and blood clotting problems when Bextra is used by patients who have just had heart bypass surgery.

In September, the COX-2 inhibitor Vioxx was recalled because it was linked to an increased risk of heart problems.

A new study of more than 1,500 patients recovering from heart surgery showed those taking Bextra for pain were more likely to have heart problems, compared to those who did not take any drugs, the FDA said.

"FDA believes that, based on what we know now, the overall benefit of Bextra outweighs the risk when used in properly selected patients as directed in the approved labeling," the regulator said on its website Thursday.

Bextra, made by Pfizer, is still helpful for approved uses such as relieving pain from osteoarthritis, the FDA added.

In the U.S., the new labels will also include a strong warning about the possibility of serious skin reactions.

By October 2004, more than 527,000 prescriptions were written for Bextra in Canada, according to IMS Health Canada. Many patients had switched to Bextra from Vioxx after the recall.