The primary objective of this study by researchers in France was to assess the clinical efficacy of an anti-inflammatory patch (Ketoprofen) versus a placebo in the treatment of pain related to ankle sprain. The secondary objective was to gather information on the safety of locally applied Ketoprofen as compared to a placebo.
Outpatients of both sexes, aged 18 to 65, who had acute benign ankle sprain of the lateral ligament were recruited to the study. A total of 164 patients took part, with 81 randomly assigned to the Ketoprofen group and 82 to the placebo group. The study consisted of a 14-day treatment period followed by a 7-day post-treatment follow-up by telephone. The patients were examined at days 3, 7, and 14.
The authors cite previous research which states that non-steroidal anti-inflammatory drugs (NSAIDs) have proved to be effective in the treatment of soft tissue injuries such as sprains, strains, and contusions. Oral NSAIDs are often adjuncts to treatment but can cause serious systemic side effects such as gastric ulcers. Applied topically, these drugs are formulated to penetrate the skin, subcutaneous fatty tissue, and muscle in amounts sufficient to exert therapeutic effects, while systemic blood levels remain low.
The authors state that topical NSAIDs offer the advantage of local, enhanced drug delivery to affected tissues with a reduced incidence of systemic adverse events, such as peptic ulcer disease and gastrointestinal hemorrhage.
The topical delivery system (TDS) patch, containing Ketoprofen has recently been developed. This patch releases Ketoprofen over 24 hours, and the active substance is continually present at the injury site. The authors claim that once-a-day application is likely to ensure better compliance, compared with creams, gels, and sprays, which often require 3 to 4 applications per day, and with currently available anti-inflammatory patches always requiring application twice a day.
Side effects, such as skin redness, irritation, and itching, nausea, diarrhea, vomiting, headache and insomnia, were reported in both the Ketoprofen and placebo groups.
Most patients in both the Ketoprofen and placebo groups improved within a one to two week period. This is typical is cases of benign sprained ankle. The authors reported more patients in the Ketoprofen getting better than the placebo group, and claimed a statistically significant difference between the two groups on the subject of treatment effectiveness.
Unfortunately, the low numbers involved in the study limit the power of the statistical analysis employed by the authors. During the two weeks of the study, 21 patients withdrew and a further number were excluded by the authors for reasons that were unclear. This left 69 and 61 patients in each respective group when more than 90 patients per group would be required to make the findings of the study statistically relevant to the general population.
One or more of the authors has declared a potential conflict of interest as specified in the AJSM Conflict of Interest statement. Valentina Reiner and Claudia Scarsi are currently employed by APR Applied Pharma Research S.A., which has licensed the product to other companies, and so may indirectly benefit financially from the findings in this research.