Topical NSAIDs As First-Line Therapy for Knee OsteoarthritisAll drugs come with benefits and possible side effects or adverse events. For anyone suffering joint pain from osteoarthritis, nonsteroidal antiinflammatory drugs are often used to reduce pain from inflammation and improve function. But since osteoarthritis is a chronic condition, that can mean taking these medications for a very long time. And that increases the risk of problems or complications.
One way around this is with the use of topical (lotions or gels applied to the skin) NSAID formulations. The results of this study show that one topical NSAID in particular may be helpful for those people who have mild to moderate knee arthritis. Diclofenac in a topical form was compared with oral diclofenac and with a placebo (pretend) topical solution.
Over 700 patients with bilateral knee osteoarthritis were included in the study. Bilateral means both knees were affected. The diagnosis was confirmed with X-rays. They were divided into five groups. One group received treatment with topical diclofenac administered through a liquid you may have heard of: dimethyl sulfoxide or DMSO. By combining the topical NSAID with DMSO, the active NSAID agent could be absorbed faster and more effectively without altering its effects. This group was also given an oral placebo tablet. Placebo means there was no active drug in the tablet.
The second group received a topical placebo (they thought it was the NSAID), but it was just the DMSO. They also took a placebo tablet. The third group received a placebo topical solution combined with DMSO at a lower level of DMSO concentration (2.3 per cent instead of 45.5 per cent) and they took an oral placebo tablet. The placebo solution with the higher percentage of DMSO was included to help show (or rule out) the effect of the DMSO as a possible treatment agent. The lower percentage DMSO solution was meant to be a test without DMSO's effects; a small amount of DMSO was added because this substance normally causes a garlic taste or odor that patients expect. Without it, the group would know they weren't getting the real NSAID.
Group four was given a placebo solution plus oral diclofenac (a slow-release pill form of the topical NSAID being tested). And the last group received both the topical and the oral forms of diclofenac. Anyone who used any of the topical solutions tested applied 40 drops of the prepared solution around the whole knee. They did this four times a day without rubbing it in.
Patients in the groups receiving a topical agent only had one knee treated. This provided a nice control group (the untreated leg). Everyone was followed for 12-weeks. They were told not to take any other antiinflammatory medications. They could take Tylenol for pain and/or any other necessary medication already prescribed before the study began (e.g., antidepressants, blood pressure medication). Before and after measures were taken of pain, stiffness, physical function, vital signs, and overall health. Routine blood and urine samples were analyzed before and after as well. And because there have been reports of vision changes with the use of DMSO in animals, a visual exam was also performed before and after treatment.
After all the data was collected and analyzed, here's what they found. First, topical diclofenac is clearly better than the topical placebo (with or without DMSO). Although pain and function were improved with the true topical diclofenac, there was no change in knee joint stiffness. Second, topical diclofenac caused fewer adverse events than the oral form. There was a little skin drying in the topical group because of the DMSO. Of particular interest was the fact that the placebo (oral) group had more gastrointestinal reactions than the topical group. The authors suspect this is as a result of the power of suggestion. Patients in the placebo group were told (just like everyone else was told) that there could be some gastrointestinal symptoms develop when using NSAIDs.
One other important finding was the fact that the DMSO was not an effective treatment itself for active, painful, and limiting knee osteoarthritis. This result helps negate commonly held (but erroneous) beliefs that DMSO is useful treatment all by itself for knee arthritis. It simply functions as a penetration enhancer assisting the NSAID in crossing through the skin.
The authors conclude that topical NSAIDs and in particular, diclofenac, can be used as the first-line treatment for patients with painful, symptomatic knee arthritis without the usual adverse effects that occur with oral doses of NSAIDs. This knowledge gives patients another treatment option early on in the sequence of events that accompany chronic knee pain from osteoarthritis. Future studies will investigate optimal solutions and doses for the topical treatment using diclofenac as well as what happens past the 12-week mark used in this study.
Lee S. Simon, et al. Efficacy and Safety of Topical Diclofenac Containing Dimethyl Sulfoxide (DMSO) Compared with Those of Topical Placebo, DMSO Vehicle and Oral Diclofenac For Knee Osteoarthritis. In Pain. June 2009. Vol. 143. No. 3. Pp. 238-245.
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