Topical Duloxetine and Ketoprofen for the Treatment of Orofacial Neuropathic Pain

Objectives: To assess baseline pain threshold level prior to any procedure
To induce orofacial neuropathic pain by chronic constriction injury of the infraorbital nerve and to assess the pain levels seven days post-surgery
To assess pain behavior and motor side effects following topical application of ketoprofen, and duloxetine in separate groups.
Methods: Sixty male adult Sprague Dawley rats were used in this study. A chronic constriction nerve injury (CCI) of the infra-orbital nerve was performed to induce chronic orofacial neuropathic pain. Rats were administered topical duloxetine, ketoprofen or a combination of both in separate groups. For behavioral assays tactile allodynia and mechanical hyperalgesia was measured, and motor coordination was measured for side effects using a Rotarod, at day 0 (baseline), days 7, 8, 9 and 10 post surgery. At day 11 post euthanasia samples of contra-lateral and ipsilateral nerve and dermis above the infra orbital region were taken to measure levels of Interleukin -6 using ELISA.
Results: Topical duloxetine reduced orofacial neuropathic pain as effectively as systemic administration with significantly less motor side effects.
Topical duloxetine significantly reduced the IL-6 levels in the dermis but not in the nerve samples.
Conclusions: The results may suggest the use of topical medications for the treatment of orofacial neuropathic pain.