The class of painkillers known as non-steroidal anti-inflammatory drugs (NSAIDs) can relieve the pain of osteoarthritis, but they may cause stomach problems. The solution might be to avoid the stomach all together.
According to a new study, a lotion made up of the NSAID diclofenac plus an absorption enhancer significantly lessens the pain and stiffness of osteoarthritis of the knee, with the only side effect being minimal skin irritation.
The lotion is made by Dimethaid Health Care Ltd. and is sold under the brand name Pennsaid, although not in the U.S.
NSAID lotions may provide an alternative to NSAID pills for treating knee osteoarthritis, study authors Drs. Sanford H. Roth from Arizona Research and Education in Phoenix and J. Zev Shainhouse from Dimethaid Health Care Ltd, in Markham, Ontario, suggest in the Archives of Internal Medicine.
The two investigators randomly assigned 326 people with osteoarthritis in at least one knee to apply 40 drops of topical diclofenac or a control solution to the affected joints four times daily for 12 weeks. Two hundred twenty eight participants completed the study.
The diclofenac lotion proved significantly more effective than the sham preparation for all outcomes, including pain, physical functioning, and stiffness.
The improvement in these areas ranged from 35 percent to 46 percent compared with the start of the trial, results that “compare favorably with conventional oral diclofenac treatment of osteoarthritis,” the authors note.
Roughly 41 percent of subjects who applied the diclofenac solution reported some minor skin irritation such as dryness or rash. There were no differences between groups in complaints of stomach problems.
Diclofenac solution is approved in Canada and several European countries for the treatment of symptomatic osteoarthritis. Currently, no topical NSAID for the treatment of osteoarthritis is approved in the US.