Skin Patch for Knee Osteoarthritis Pain?

Lidoderm Patch Could Help, Says Study by Drug's Maker

By Miranda Hitti
WebMD Medical News

Reviewed By Michael Smith, MD
on Friday, April 01, 2005

April 1, 2005 - A skin patch called Lidoderm may help ease pain caused by knee osteoarthritis , giving patients an alternative to the drug Celebrex.

Celebrex is a Cox-2 inhibitor -- a class of drugs that has drawn attention for possible heart attack and stroke risks. In February, an FDA expert panel recommended that Celebrex and its sister drug Bextra remain on the market despite this risk. Official word from the FDA is expected in the next few weeks.

Recent developments regarding these drugs have left many patients concerned about what arthritis drugs are safe for them to take.

Osteoarthritis is the most common type of arthritis. It involves the gradual breakdown of cartilage in joints. Knee osteoarthritis can be painful and even disabling.

The Lidoderm patch isn't approved for knee osteoarthritis pain. It's only been approved for treating pain from postherpetic neuralgia. That's a chronic condition resulting from nerve damage caused by shingles.

Lidoderm Takes On Celebrex

Lidoderm's maker, Endo Pharmaceuticals, sponsored a comparison of Celebrex and Lidoderm in knee osteoarthritis patients. The findings were presented at the American Pain Society's annual meeting.

Originally, the researchers planned to enroll 200 patients. But when Cox-2 drugs became controversial last fall, they stopped adding new patients. That left 143 patients, all of whom had knee osteoarthritis pain.

First, the patients stopped taking all pain medications, as well as the supplements chondroitin and glucosamine. After a week or two, they were randomly assigned to take Celebrex or use the Lidoderm patch for 12 weeks.

The active ingredient in the Lidoderm patch is the pain-numbing medication lidocaine. The patch is applied once daily.

Significant Improvement With Both Treatments

Results were based on patient's ratings of their knee osteoarthritis pain. After six weeks, 62% of the Celebrex group and 54% of the Lidoderm group reported at least a 30% improvement in the average daily intensity of their knee pain. By the 12th week, the numbers had risen to about 71% of each group.

A pain improvement of 30% or greater is considered scientifically meaningful.

Both treatments were well tolerated. Side effects were reported in about 11% of both groups. Three Lidoderm patients dropped out because of side effects; the most common side effects were itchiness or redness at the patch site. No Celebrex patients quit because of side effects.

Another Option for Knee Arthritis?

"The results of this exploratory study examining Lidoderm and Celebrex suggest that Lidoderm can alleviate the pain associated with osteoarthritis of the knee," says Alan Kivitz, MD, in a news release.

"I am encouraged by these findings since there is a critical need for new approaches to managing this type of pain," says Kivitz, who worked on the study and is based at Pennsylvania's Altoona Center for Clinical Research.

SOURCES: 24th Annual Scientific Meeting, American Pain Society, Chadds Ford, Pa., March 30-April 2, 2005. News release, Endo Pharmaceuticals. WebMD Medical Reference provided in collaboration with The Cleveland Clinic: "Osteoarthritis Basics." WebMD Medical Reference from Healthwise: "Shingles --Topic Overview."

© 2005 WebMD Inc. All rights reserved



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