Drug therapy of neuropathic pain: current developments and future perspectives

Understanding mechanism of neuropathic pain is too complex and involves both peripheral and central pathophysiological phenomenon. Accordingly the treatment of neuropathic pain is also very complex and is unsatisfactory. The present review attempts to discuss the currently employed pharmacological agents for the management of neuropathic pain including anti-depressants, anti-convulsants, NMDA receptor antagonists, topical & local anesthetics, and upload analgesics. However, the existing pharmacotherapy has marginal efficacy and significant side effects. The review also gives an insight into various pharmacological agents with potential neuropathic pain attenuating properties in experimental models that include NSAIDs, corticosteroids, ion channel blockers (Ca(2+), Na(+), K(+), and TRP channel); ion exchange modulators (NCE and NHE); ion/molecule transport modulators (NKCC-1 and glycine); receptor modulators (kinin, histamine, 5-HT1A, dopamine, alpha & beta adrenergic, purinergic, excitatory amino acid, sigma, ORL1, endothelin, melanocortin, ephrin and PAR); enzyme inhibitors (cytosolic kinase, metalloproteinase, protease, vasopeptidase, D-amino acid oxidase, fatty acid amide hydrolase, aldose reductase and sorbitol dehydrogenase); other ligands (AGE, RAGEs, neuropeptides, neurotrophic factor, complement cascade, cytokine, glial cell & gap junction, nitrous oxide, growth factor, cell adhesion molecule and neuronal sprouting molecule). Moreover, some advanced therapeutic approaches such as neuronal cell transplantation, stem cell therapy, anti-sense oligonucleotide and recombinant therapy have also been dicussed.