Capsaicin 8% patch is well-tolerated and provides significant improvements in pain and sleep quality compared with placebo for patients with painful diabetic peripheral neuropathy (PDPN), according to a study presented here at the 51st Annual Meeting of the European Association for the Study of Diabetes (EASD).
Capsaicin 8% patch has been used as an analgesic for patients with post-herpetic neuralgia and HIV-associated distal sensory polyneuropathy. It is also indicated for treatment of peripheral neuropathic pain in non-diabetic adults.
“The efficacy and safety of this patch in patients with painful diabetic peripheral neuropathy has not been fully characterised,” said Malcolm Stoker, PhD, Global Medical Lead, Astellas Pharma Global Developments, Leiden, the Netherlands.
The objective was to determine efficacy and safety of a single application of capsaicin 8% patch compared to placebo in these patients.
Patients were randomised to placebo patch (n = 183) or capsaicin 8% patch (n = 186), as a single treatment of 1 to 4 patches applied to the painful area of the feet for 30 minutes. Patient blinding was aided by pre-treatment of all painful areas with lidocaine 2.5% and prilocaine 2.5% for patch application.
The primary endpoint was mean percentage change in average daily pain score from baseline to weeks 2 to 8. Here, compared with placebo (-20.9), capsaicin 8% patch showed significant improvement (-27.4), for least square mean difference of -6.6 (P = .025). This difference was also maintained for weeks 2-12 (-7.1; P = .018).
Among the secondary efficacy endpoints, there was significant benefit for active treatment for mean percentage change in sleep interference score (weeks 2-8: -24.2 vs -33.1, least square mean difference -9.0, P = .030; weeks 2-12: -24.7 vs. -34.0, least square mean difference -9.5, P = .020).
Patient Global Impression of Change was numerically in favour of active treatment at weeks 8 (P = .075) and 12 (P = .169).
In the safety analysis, there were similar levels of treatment-emergent adverse events (TEAEs) for placebo and capsaicin 8% patches (33.9% vs 46.8%), and these were mainly application site reactions (8.2% vs 33.9%), including burning sensation (2.7% vs 14.0%) and pain in extremity (5.5% vs 10.8%).
There were no discontinuations for drug-related TEAEs, and there were no deaths or drug-related serious TEAEs.
“This study extends the range of peripheral neuropathic pain aetiologies for which the capsaicin 8% patch has shown both efficacy and safety,” said Dr. Stoker.