Lidocaine patch may help reduce osteoarthritic knee pain

Clinically meaningful pain reductions noted after treatment with Lidoderm (lidocaine patch 5%) or Celebrex (celecoxib 200 mg) at six weeks, researchers said

Results from a recent clinical study suggest a lidocaine-containing patch can help reduce knee pain associated with osteoarthritis, according to Endo Pharmaceuticals Inc., the study’s sponsor and makers of the patch.

Alan Kivitz, MD, a physician at the Altoona Center for Clinical Research, Pa., and colleagues conducted the study. The researchers randomly assigned 69 patients to treatment with one Lidoderm (lidocaine patch 5%) applied to the front and one-third of a patch to the back of each affected knee daily, and 74 patients to treatment with Celebrex (celecoxib 200 mg, Pfizer) once daily.

The researchers intended to review 200 patients, but Endo Pharmaceuticals voluntarily halted the study prematurely due to the safety concerns over COX-2 inhibitors last fall, the company noted.

Patients discontinued all analgesic medications, chondroitin and glucosamine for seven to 14 days before start of the study. At baseline, patients had an average daily pain intensity of at least 5 on a 10-point scale for at least three of five consecutive days. They also had an OA severity of at least 7 on a 24-point scale.

The final data included 56 Lidoderm patients and 63 Celebrex patients. At six weeks follow-up, 54% of Lidoderm- and 62% of Celebrex-treated patients experienced a clinically meaningful reduction of 30% or more in average daily pain intensity. Clinically meaningful reductions were also noted in both groups at 12 weeks follow-up, according to the press release.

“The results of this exploratory study examining Lidoderm and Celebrex suggest that Lidoderm can alleviate the pain associated with osteoarthritis of the knee,” Kivitz said in the release.

“Although these results need to be confirmed with further randomized controlled trials, the potential of Lidoderm to treat osteoarthritis knee pain is promising,” he said.

Eight patients in each group did experience adverse events, most commonly itchiness or redness at the patch site. Three Lidoderm-treated patients also discontinued the study due to adverse events.

Lidoderm was approved by the FDA in 1999 to treat pain associated with post-herpetic neuralgia (PHN), a chronic condition resulting from nerve damage caused by shingles. Up to three patches can be applied for up to 12 hours within a 24-hour period, according to the company.

Lidoderm has not been FDA-approved for any other indications other than pain associated with PHN, and its safety and efficacy for other indications has not been established, the company noted.

For more information:
Galer B, Kivitz A, Fairfax M, et. al. A randomized, open-label study comparing the efficacy and safety of lidocaine patch 5% with celecoxib 200 mg in patients with pain from osteoarthritis of the knee. Poster #771. Presented at the 24th Annual Scientific Meeting of the American Pain Society. March 30-April 2, 2005. Boston.