Topical diclofenac safely relieves clinical neuropathic pain

By Reuters Staff

NEW YORK (Reuters Health) - Topical diclofenac (1.5%) provides moderate pain relief in some patients with clinical neuropathic pain, according to results from a small, randomized crossover trial.

"Given the challenge of treating neuropathic pain and the minimal side effect of topical diclofenac, we believe it has a role in managing neuropathic pain," Dr. Shihab U. Ahmed from Harvard Medical School in Boston told Reuters Health by email. "For neuropathic pain conditions with cutaneous hypersensitivity, topical diclofenac would be a reasonable option based on its safety profile and favorable impact on pain relief."

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly prescribed to treat neuropathic pain, but topical NSAID preparations have not been carefully evaluated for its treatment.

Dr. Ahmed and colleagues, in a 28-patient crossover study, investigated whether two weeks of treatment with 1.5% topical diclofenac (versus matching topical placebo) reduced pain and improved functional status associated with neuropathic pain.

After two weeks, visual analog scores (VAS) for pain were significantly lower with topical diclofenac than with placebo (4.9 vs. 5.6; p=0.04), the researchers report in Anesthesiology, online May 8.

The greatest improvements were seen in burning pain (a 1.4-point difference in favor of diclofenac), with smaller improvements in constant pain and hypersensitivity (a 0.3-point difference in favor of diclofenac). Shooting pain did not change significantly with either treatment.

There was no significant change in results of static quantitative sensory testing (QST) with treatment, but there were significant decreases in temporal pain summation after two weeks of diclofenac treatment.

The only statistically significant functional change was a slight improvement in psychological health scale averages for the placebo treatment.

Patients reported no complications or side effects with either diclofenac or placebo treatment.

Dr. Ahmed cited further evidence in support of diclofenac that did not appear in the report. For example, he said, "16 subjects using the study drug versus 7 subjects using the placebo reported greater than 30% pain relief (p=0.04)."

Patients also self-reported less hypersensitivity of the painful area during topical diclofenac treatment, he said.

"We should consider additional clinical investigations to further explore the efficacy of topical diclofenac on neuropathic pain conditions while limiting its use to neuropathic pain conditions with cutaneous hypersensitivity until further evidence is available," Dr. Ahmed concluded.

Covidien funded this work in response to an investigator-initiated research proposal. The authors declared no competing interests.

SOURCE: http://bit.ly/1LQ0uyM

Anesthesiology 2015.

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