Filed at 4:28 p.m. ET

CHICAGO (AP) -- The popular painkiller Vioxx has been linked to five cases of a nonbacterial type of meningitis, a possible side effect that, although rare, is serious, the U.S. Food and Drug Administration reports.

The cases are among seven reported to the FDA from May 1999 -- when it approved Vioxx for arthritis and other acute pain -- through February 2001, according to the report in Monday's Archives of Internal Medicine.

Some 52 million Vioxx prescriptions have been written in the United States since June 1999, a spokeswoman for Merck & Co. said.

All seven patients were taking Vioxx when they developed meningitis, but two cases lacked enough information to determine possible causes, the report said.

Since February 2001, meningitis also has been reported in five other Vioxx patients, but those cases have not been evaluated in detail, said Renan Bonnel of the FDA's Center for Drug Evaluation and Research, an author of the report.

No one has died in any of the cases, Bonnel said.

The report notes that other nonsteroidal anti-inflammatory drugs, including ibuprofen and naproxen, also have been linked in rare cases to meningitis. Celebrex, a drug similar to Vioxx, has been linked to six cases of meningitis but the reports ``contain very little or no information to assess causality,'' Bonnel said.

The Vioxx patients described in Archives were ages 16 to 67 and developed symptoms up to 12 days after starting the drug. Symptoms included headache, stiff neck, eye pain, fever and chills.

``All cases were serious, requiring hospitalization,'' the report said.

The diagnosis was aseptic meningitis, inflammation of the brain and spinal cord that is not caused by bacteria and is generally less severe than bacterial meningitis. It is sometimes caused by a virus or a medication and the FDA report doesn't say it was definitely caused by Vioxx.

However, the FDA has required Merck to add meningitis to the list of potential side effects included on the Vioxx product label and package insert.

Merck spokeswoman Chris Fanelle said that just because an adverse event occurs in patients ``does not prove that the drug causes it,'' and the reported cases represent a tiny fraction of the 52 million Vioxx prescriptions.

``This is a rare event and we don't think this is cause for worry,'' Fanelle said.

Vioxx also has been scrutinized for data that some say suggests a possible link to heart attacks, though Merck disputes that conclusion.

^------

On the Net:

Archives: http://archinte.ama-assn.org/

FDA: http://www.fda.gov/

Vioxx: http://www.vioxx.com/