WASHINGTON – Some of the world’s largest drugmakers will face an uphill battle next week in their bid to revive a class of experimental pain drugs that have been sidelined by safety concerns for nearly two years.

The Food and Drug Administration says there is a clear association between the nerve-blocking medications and reports of joint failure and bone deterioration that led the agency to halt studies of the drugs in 2010. However, the agency also notes that those side effects were less common when the drugs were used at lower doses, potentially leaving the door open for future use. The agency released its safety analysis ahead of a public meeting next week where outside experts will discuss the drugs’ safety.

On Monday, Pfizer Inc., Johnson & Johnson and Regeneron Pharmaceuticals will make their case to continue studies of the drugs, with new safety precautions to protect patients.

The request to restart testing is unusual, because drugmakers often abandon research on experimental drugs that appear to have safety issues. However, with more than 50 million U.S. adults diagnosed with arthritis — one in five — the potential multibillion dollar market opportunity may be too big to ignore.

In three completed studies of Pfizer’s tanezumab, the injection provided more pain relief than Aleve or oxycodone, according to company documents posted online.

If the drugs eventually win FDA approval, they may be used for much narrower indications than initially envisioned. The FDA’s questions for its expert panel appear designed to limit any future testing of the drugs.

Drugmakers once touted the drugs, known as nerve growth factor inhibitors, as a potential breakthrough for treating osteoarthritis, back pain and other chronic pain conditions.