Topical creams with Capsaicin are used to treat pain from a wide range of chronic conditions including neuropathic pain. Following application to the skin Capsaicin causes enhanced sensitivity to noxious stimuli, followed by a period with reduced sensitivity and, after repeated applications, persistent desensitisation. There is uncertainty about the efficacy and tolerability of Capsaicin for treating painful chronic neuropathies.

Researchers at University of Oxford ( UK ) have assessed efficacy and tolerability of topically applied Capsaicin in chronic neuropathic pain in adults.

Six studies ( 389 participants in total ) compared regular application of low dose ( 0.075% ) Capsaicin cream with placebo cream; the number needed to treat ( NNT ) for any pain relief over six to eight weeks was 6.6.

Two studies ( 709 participants in total ) compared a single application of high dose ( 8% ) Capsaicin patch with placebo patch; the NNT for greater than or equal to 30% pain relief over twelve weeks was 12.

Local skin reactions were more common with Capsaicin, usually tolerable, and attenuated with time; the number needed to harm ( NNH ) for repeated low dose application was 2.5.

All studies satisfied minimum criteria for quality and validity, but maintenance of blinding remains a potential problem.

In conclusion, Capsaicin, either as repeated application of a low dose ( 0.075% ) cream, or a single application of a high dose ( 8% ) patch may provide a degree of pain relief to some patients with painful neuropathic conditions. Local skin irritation, which is often mild and transient but may lead to withdrawal, is common. Systemic adverse effects are rare. Estimates of benefit and harm are not robust due to limited amounts of data for different neuropathic conditions and inconsistent outcome definition.

Derry S et al, Cochrane Database Syst Rev 2009;(4):CD007393

XagenaMedicine2009


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