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Pain Drugs Linked to Bone Death Under Review

(Image: © Dreamstime)

An advisory panel for the Food and Drug Administration will weigh in today (March 12) on whether drug companies can resume trials of pain drugs for osteoarthritis.

Testing of the drugs, known as anti-nerve growth factor (anti-NGF) drugs, was halted by the FDA in 2010 and early 2011 after some patients taking them experienced bone tissue death in the joints, and required joint replacements. No cases of joint tissue death were seen in patients in the studies who took a placebo.

Three drugs companies — Pfizer, Johnson & Johnson and Regeneron Pharmaceuticals — were testing anti-NGF drugs before the trials were stopped. Pfizer's drug, tanezumab, was the farthest along in trials.

Today's meeting is unusual in that the panel will be discussing drugs that are not already approved by the FDA or under review for approval, Bob Rappaport, director of the FDA's division of anesthesia, analgesia, and addiction products, said in a memo to the meeting's attendees.

Anti-NGF drugs block nerve growth factor, a protein that is important for the development and survival of certain nerve cells also thought to cause sensitivity to pain in certain conditions.

A 2010 study of 450 patients with knee osteoarthritis found tanezumab reduced pain by 45 to 62 percent, compared with a placebo that reduced pain by 22 percent.  But after the study ended, 16 patients taking tanezumab experienced bone tissue death in their knee, hip or shoulder joints and required joint replacements.

In more than half the patients, the joint that needed replacing was not the joint that was being evaluated in the study. The study, sponsored by Pfizer, was published in the New England Journal of Medicine in September 2010.

Osteoarthritis is a form of arthritis in which the cartilage in a joint breaks down, leading to bone rubbing on bone.

Pfizer says the joint destruction seen in the study was due to taking the anti-NGF drug along with nonsteroidal anti-inflammatory drugs(NSAIDs), such as aspirin or ibuprofen, and therefore the adverse events can be prevented.

The FDA committee will review new reports from the drug companies and decide whether they agree.

In an editorial accompanying the 2010 New England Journal of Medicine study, John N. Wood, of University College London, said the joint destruction seen in some patients in the study was likely due to excessive wear and tear on the joints that occurred because the patients did not experience joint pain. The study "suggests that a complete quenching of pain in patients with osteoarthritis may not necessarily be a good thing," Wood wrote.

Pass it on:  Use of an experimental class of pain drugs has been linked to joint destruction, and the FDA will decide whether trials of the drugs can continue.

This story was provided by MyHealthNewsDaily, a sister site to LiveScience. Follow MyHealthNewsDaily staff writer Rachael Rettner on Twitter @RachaelRettner. Find us on Facebook.