Menthol in topical creams relieves Osteoarthritis pain

Apr 19 2004

Osteoarthritis (OA) is a progressive, degenerative joint disease estimated to affect more than 21 million individuals in the United States.

The Arthritis Foundation reports that arthritis is the leading disability of Americans resulting in over 39 million medical visits per year and $65 billion in medical expenses and lost wages. This condition is characterized by erosion of articular cartilage, caused by enzymatic and mechanical breakdown of the extracellular matrix.

The most common symptoms are pain, stiffness, reduced joint range of motion, and limitations to normal activities of daily living such as getting up from a chair, walking, balance and strength, and ascending/descending stairs, as well as limitations to local muscular endurance and hand grip strength in patients with OA of the upper extremities.

Pain reducing medications such as acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs), and COX-2 inhibitors have been common treatments for osteoarthritis in the growing elderly population. However, these medications often have painful side effects or do not react well with other medications. Accordingly, there is a need for alternative treatments for the osteoarthritis patient.

One proven alternative treatment is the use of oral and/or a topical blend of cetylated fatty acids. Cetylated monounsaturated fatty acids have been shown to provide protection against arthritis in rats; a recent study demonstrated that a topical cream consisting of a blend of cetylated fatty acids significantly reduced pain and improved physical function in patients with knee osteoarthritis. In that study, the first treatment of the topical cream caused acute improvements in stair climbing ability, timed "up and go" performance, knee range of motion, and a reduction in pain within 30 minutes. Additional improvements were observed after 30 days of treatment. However, this research was for the topical cream in its developmental stage and was only used with patients with knee osteoarthritis.

A New Study
Recently, menthol has been added to this topical cream. Menthol has been shown to possess analgesic properties thereby reducing the sensation of pain. A new study extends previous research and examines the effects of a topical cream consisting of cetylated fatty acids, along with the addition of menthol, on pain and functional performance in patients with knee osteoarthritis over the course of one week. Additionally, several patients with elbow and wrist osteoarthritis were included to examine potential effects on upper-extremity performance and pain in these individuals.

The authors of "Treatment With A Cetylated Fatty Acid Topical Cream With Menthol Reduces Pain and Improves Functional Performance In Patients With Osteoarthritis," are Nicholas A. Ratamess, William J. Kraemer, Jeffrey A. Anderson, David P. Tiberio, Michael E. Joyce, Barry N. Messinger, Jeff S. Volek, Duncan N. French, Matthew J. Sharman, Ana L. Gómez, Barry A. Spiering, Jason D. Vescovi, Ricardo Silvestre, Carl M. Maresh, and Robert L. Hesslink Jr. The participating institutions were the Human Performance Laboratory, University of Connecticut, Storrs, CT; Department of Health and Exercise Science, The College of New Jersey, Ewing, NJ; and Imagenetix, Inc., San Diego, CA. The researchers will present their findings at the American Physiological Society’s (APS) (http://www.the-aps.org) annual scientific conference, Experimental Biology 2004, being held April 17-21, 2004, at the Washington, D.C. Convention Center.

Methodology
Twenty-eight patients (10 with knee OA, 10 with wrist OA, 8 with elbow OA) were assigned to an experimental group based upon the location of his/her diagnosed osteoarthritis (i.e., knee, elbow, or wrist). Each patient applied the cream to the affected area twice per day every day for one week and subsequently returned to the lab for post-study functional performance testing. Subjects were tested for pain, stiffness, knee range of motion (ROM), balance, and ability to rise from a chair, walk, and ascend/descend stairs for patients with knee osteoarthritis; patients with elbow and wrist osteoarthritis were tested for measures of grip strength, elbow ROM, muscular strength, local muscular endurance, and pain.

The significant improvements observed in the research team’s previous investigation with use of a topical cream consisting of a blend of cetylated fatty acids, coupled and the high test-retest reliability (R = 0.95 to 0.99), precluded the need for a control group for this study.

Results
Fifteen test results were obtained for patients with osteoarthritis of the knee, twelve for patients having OA in the elbow, and eight measurements were taken with patients diagnosed with wrist osteoarthritis. Across the board, the test measurements (available upon request) revealed that use of a cetylated fatty acid topical cream with the addition of menthol produced significant improvements in physical performance and reduced pain in patients with OA of the knee, wrist, and elbow.

Conclusions
Topical creams containing cetylated fatty acid are now being sold to consumers for the knee osteoarthritis. This study demonstrates that the addition of menthol adds a new pain relief component to the treatment and its effectiveness for osteoarthritis of the knee, elbow and wrist.

The American Physiological Society (APS) is America’s oldest biomedical sciences research society. The not-for-profit society, with some 11,000 members, is the publisher of 14 scientific journals, including the American Journal of Physiology, which has been published since 1898.