Pretreatment Identification of Duloxetine Success in Neuropathic Pain Patients Based on Assessment of Endogenous Analgesia Capabilities

There is no accepted practice for selecting among recommended medications for the individual neuropathic pain patient. Guidelines published to date provided the evidence for their efficacy, however, data is not available on how to choose the right medication for the right patient in order to avoid long 'trial and error's. We hypothesize that medications affecting specific process of pain modulation will be more efficacious in patients expressing dysfunction of that specific process. Therefore, medications that enhance descending inhibition such as SSNRI will be more efficacious in patients with less-efficient pain inhibition. The latter is assessed by the conditioned pain modulation (CPM) paradigm. Accordingly, the aim of this study is to examine this hypothesis in painful diabetic neuropathy patients, using duloxetine, an SSNRI agent assumed to augment descending pain inhibition by reuptake inhibition of noradrenalin and serotonin in the spinal cord dorsal horn synapses. We expect to find better effect of duloxetine in those patients whose pain inhibition capability is less efficient, as expressed by their baseline CPM. Further, we aim to evaluate whether pro-nocieptive pattern of pain modulation indeed reverses in response to treatment. This will be explored by comparing the CPM responses before and after treatment, and by correlating pain alleviation with the possible changes in CPM.