Diclofenac has emerged on top in a new Cochrane review of topical NSAIDs, amid a fresh FDA warning about serious burns with some over-the-counter pain-relievers.
“Topical diclofenac is about as effective as oral diclofenac in osteoarthritis of the knee or hand, and probably as effective as other NSAIDs,” concluded the authors after reviewing 34 high-quality studies involving 7688 participants.
Overall, reviewers found topical NSAIDs were “significantly more effective than placebo” for reducing chronic musculoskeletal pain, but that diclofenac had the best data behind it.
Relative to placebo, the number needed to treat for at least 50% pain relief over eight to 12 weeks was 6.4 for the solution and 11 for the gel formulation.
There was too little data to formulate similar comparisons in the other NSAIDs, the authors said.
Topical NSAIDs were more likely than placebo or oral NSAIDs to cause local adverse events, mainly mild skin reactions, but investigators found no increase in serious adverse events.
Oral NSAIDs were more likely to cause gastrointestinal grief than topical NSAIDs, which were no different to placebo.
A study covered by Rheumatology Update in February proposed an “exponential” link between oral diclofenac and Clostridium difficile-associated diarrhoea.
The review came just days before the FDA warned on Thursday it had received reports of serious chemical burns with single or combination topical pain relievers containing menthol, methyl salicylate and capsaicin.
Numerous products containing such ingredients are available over-the-counter in Australia, including Mentholatum Deep Heat.
“These products should not cause pain or skin damage,” the FDA said in a statement. “However, there have been rare cases of serious burns following their use. Some of the burns had serious complications requiring hospitalisation.
Most second- and third-degree burns occurred with products with menthol as the single active ingredient and products containing both menthol (at more than three percent) and methyl salicylate (at greater than ten percent).
The Cochrane Library 2012; DOI: 10.1002/14651858.CD007402.pub2