Patients On Warfarin Should Avoid Cox-2 Drugs Like Celebrex: Study
Jan 24, 2005 | CP Older patients taking the blood-thinner warfarin have an elevated risk of potentially deadly stomach bleeding if they also take common anti-inflammatory drugs for arthritis, a Canadian study suggests.But the danger isn't limited to drugs such as ibuprofen and Naproxen. Celebrex, Bextra and others among the much-talked-about class of drugs known as Cox-2 inhibitors also pose a risk, says Muhammad Mamdani, a senior author of the study by the Institute of Clinical Evaluative Sciences, or ICES.
"So first and foremost, if you're on Coumadin (warfarin), and you need to take one of these drugs, be careful because your risk of bleeding doubles," Mamdani, an expert in pharmacology and health research, said in an interview Monday.
Warfarin, taken by thousands of older Canadians to prevent heart attacks and strokes from blood clots, makes it more difficult to stop bleeding from a cut or other injury.
It's long been known that ibuprofen and other NSAIDs, or non-steroidal anti-inflammatory drugs, increase the risk of upper gastrointestinal bleeding because they can irritate the stomach lining and also boost the likelihood of bleeding.
Early studies suggested Cox-2 inhibitors like Celebrex were "safer on the gut than traditional NSAIDs," said Mamdani. "Our study was finding they both have the same rates of GI bleed."
And the condition can be dangerous: about one in 10 patients with a serious stomach bleed die before making it to hospital for life-saving surgery, he said.
The researchers analysed several prescription and health-care databases in Ontario, looking at patients over age 66 who were on warfarin during a yearlong study in 2000-2001. They found that those admitted to hospital for gastric bleeding were more likely to be taking NSAIDs or Cox-2 inhibitors along with the blood-thinner.
The study is published in this week's issue of the Archives of Internal Medicine.
Mamdani said the analysis also showed that "physicians seem to be a little more lax in prescribing the Cox-2 inhibitors," noting that twice as many older people on warfarin are given a Cox-2 compared with NSAIDs.
"There might be a perception out there that these drugs are so safe, it doesn't matter what (other medications) you're on. That's a little bit worrisome because there may be a false sense of comfort with these drugs."
Mamdani said doctors treating patients on warfarin should carefully assess their need for an anti-arthritis drug, and if they don't need it, "don't put them on it."
Patients on the blood-thinner should also avoid dosing themselves with over-the-counter NSAIDs like Advil, one of the many ibuprofen drugs, without checking with their physician, he said, suggesting that exercise, rub-on remedies and other non-drug therapies can alleviate the pain and stiffness of osteoarthritis in joints.
Dr. Jim Wright, a clinical pharmacologist and internist at the University of British Columbia, said the study has major implications because a lot of physicians would likely choose Cox-2s for arthritis patients already on warfarin, believing the drugs have a lower risk than NSAIDs.
But Wright said that assumption is wrong and has not been backed up by previous studies.
"I've been saying for a long time that these drugs are probably more harmful than beneficial compared to NSAIDs I've been recommending not to use these until there's clear evidence that they're safer. And that hasn't happened.
"And the evidence we have right now suggests we shouldn't use them."