Neuropathic pain and its treatment with ARA 290 and ketamine : overlapping pathways

Abstract

Neuropathic pain is a disabling disease with a mechanism consisting of several pathways that ultimately converge in the development and persistence tactile and cold allodynia. Pharmacological treatment is often inadequate and coincides with intolerable side effects. The spared nerve injury animal model of neuropathic pain was employed as a method for evaluating the effect of the 11-amino acid tissue protective peptide ARA 290, and the NMDA receptor antagonist ketamine on behavioral and cellular responses after nerve injury and comparison of these two drugs. Clinically, pain is a subjective outcome that can be measured by numerical rating scales or questionnaires. Due to this subjectiveness it is not reliable for diagnosing small fiber neuropathy (SFN). Therefore, SFN is being diagnosed by invasive method of intra-epidermal nerve fiber density evaluated with microscopy. Alternatively, the cornea has a high density of small nerve fibers that can be evaluated by the non-invasive method of corneal confocal microscopy. Finally, the effect of ARA 290 on nerve fiber loss and corneal nerve fiber density in sarcoidosis patients in a double-blind-randomized clinical study was evaluated that showed that ARA 290 is a potential disease modifying agent for treatment of sarcoidosis-associated SNFLD.