Pfizer's Celebrex Under Review
Risks linked to arthritis drug prompt caution; FDA will examine dataDec 18, 2004 | www.theday.com Pfizer Inc.'s announcement Friday morning that Celebrex, its widely prescribed arthritis medication, showed increased risk of heart attacks and strokes in patients taking higher than normal doses prompted some doctors to decide not to write new prescriptions for the drug as they await more information about its safety.
“I have stopped prescribing Celebrex as of today, until the safety profile is clarified,” said Dr. Vijay Sikand, who practices family medicine and gerontology and is medical director of the Visiting Nurse Association of Southeastern Connecticut.
The cardiovascular risks cited by Pfizer were similar to those that caused the withdrawal two months ago of Vioxx, a similar drug made by Pfizer competitor Merck & Co. After Vioxx was pulled off the market, many patients were switched to Celebrex and Bextra, a stronger Pfizer painkiller, boosting sales significantly. Pfizer, noting that the higher risks emerged in only one of two long-term studies and that numerous previous studies have verified the safety of Celebrex, said it would continue to offer Celebrex and conduct further studies. Celebrex, Bextra and Vioxx are all COX-2 inhibitors, a relatively new drug family.
“We have two conflicting results from these studies,” said Mary Ann Caprino, a Pfizer spokeswoman. “Both studies were with cancer patients taking four to eight times the recommended daily dose for arthritis patients. It does not mirror how arthritis patients typically use this medicine.”
In response to the Pfizer announcement, the federal Food and Drug Administration said Friday afternoon that it would review all data from the studies and from the dozens of other ongoing trials involving Celebrex. Once that work is complete, it will determine whether it will take regulatory action.
In the meantime, the FDA advised doctors to consider switching patients to other medications. If Celebrex is still considered the best choice for an individual patient, the FDA said, doctors should prescribe the lowest dose possible.
Dr. Sandeep Varma is among local doctors heeding the FDA's advice.
“We are being a lot more careful,” said Varma, medical director of the Rheumatology Department at The William W. Backus Hospital in Norwich. “For patients who are really apprehensive, it makes sense for them to stop taking it.”
After the Vioxx withdrawal, the FDA announced that in February it would re-examine the safety of all COX-2s. In the last two weeks, it also told Pfizer to add new warnings to Bextra labels noting the risks of giving the drug to those who had recently had heart bypass surgery.
Dr. Varma said that for now, he won't write any new Celebrex prescriptions. Patients currently taking the drug, he said, should see their doctors to consider all alternatives. They might also consider a lower dose of Celebrex, or taking it every other day instead of every day, he said.
Dr. Sikand said he also is directing his current Celebrex patients to use a different anti-inflammatory, such as ibuprofen or naproxen, at least temporarily. He estimated that he has written hundreds of prescriptions for Celebrex for pain relief for short- and long-term conditions. It is Pfizer's fifth-largest selling drug and has been the most popular of the COX-2 inhibitors, which interfere with production of the body's inflammation-causing enzyme, cyclooxygenase2.
“Celebrex is not a life-saving drug, and we have many alternatives,” said Dr. Sikand. “When such information becomes available, it behooves you to act on it.”
Other doctors, however, remain confident in the safety of Celebrex at standard doses of 100 to 200 milligrams daily and continue to believe that its benefits to patients, mainly relief of pain and inflammation without gastrointestinal bleeding, outweigh the risks.
“There's a lot of drugs that if you give too much, you're going to have problems,” said Dr. William White, professor and cardiologist at the University of Connecticut Health Center in Farmington, adding that he has never prescribed more than 200 milligrams per day.
All three doctors also noted that every medication, even those that have been in use for decades, pose some risks.
White said Pfizer acted responsibly by releasing the information about the studies within hours after seeing the data. Merck has come under sharp criticism for withholding potentially damaging study results about Vioxx long before it withdrew the drug.
The studies at the heart of Friday's announcement involved testing the use of Celebrex to prevent cancerous colon polyps in those who have previously had polyps removed. It is one of dozens of studies being conducted at hospitals and medical centers across the country to determine if Celebrex is an effective treatment for conditions for which it is not currently approved, such as various types of cancer and Alzheimer's disease.
The colon polyps study, conducted by the National Cancer Institute, found that patients taking 800 milligrams of Celebrex daily were 3.4 times more likely to have a heart attack, stroke or other serious cardiovascular event than those taking a placebo, according to the FDA. Patients taking half that amount had a 2.5 percent greater risk, the FDA said. Patients had been taking Celebrex for an average of almost three years.
The FDA noted that a similar comparison study, involving patients taking 400 milligrams of Celebrex daily, showed no increased risk.
The two studies involved 3,600 patients.