Kaiser Permanente (search), the nation's largest not-for-profit managed-care provider, has stopped prescribing Bextra (search) until tests show whether the painkiller is safe.

The decision came amid "compelling" evidence of heightened heart risks associated with Bextra and a similar drug calledVioxx (search) that manufacturer Merck & Co. pulled from the market in September, according to a company memo Kaiser issued late Friday.

Kaiser spokeswoman Beverly Hayon said the policy, which Kaiser is calling a moratorium, represents the first time the health system's doctors had decided to stop dispensing a drug that was approved by the Food and Drug Administration.

The Oakland-based HMO, hospital and clinic network, which serves 8.5 million patients in nine states and the District of Columbia, plans to stop filling new prescriptions for Bextra on Feb. 1 and on March 1 for refills.

Physicians will be notified with suggestions for alternative medicines they can prescribe. Bextra, made by Pfizer Inc., is most often recommended for arthritis patients.

"This is not a drug that saves lives," said Dr. Sharon Levine, who oversees medication usage for Kaiser Permanente's Northern California division. "It's a drug that provides a modest degree of pain relief — no better than Motrin — and the size of the risk, given the benefit provided, did not seem warranted."

The moratorium will last at least six months or "until the FDA and/or Pfizer can provide substantiated evidence to support the cardiovascular safety" of Bextra, the memo said.

The Kaiser doctors who reviewed Bextra's "safety profile" cited several studies that have raised concerns about whether the drug might increase the risk of heart attacks. They also noted that Bextra is in the same class of drugs as Vioxx, the painkiller Merck pulled from distribution after its own studies showed increased heart attack risks in elderly patients.