Emerging therapeutic strategies for chronic pain

Abstract

Chronic pain affects a high percentage of the general population. Traditional therapies based upon non-steroidal anti-inflammatory drugs (NSAIDs), opioids and co-analgesic therapies, such as antidepressant or anti-epileptic drugs, are often relatively ineffective in treating chronic pain. In addition, the low therapeutic indexes and, in particular, the often-intolerable side effect profiles of conventional compounds, limit their usefulness, especially in the elderly population. Despite intensive research, until recently there was little change in the classes of drugs available to treat chronic pain clinically. This was partly due to a failure to understand which physiological processes are important in mediating clinical chronic pain. Recently, however, greater understanding of the neurophysiology critical to chronic pain development has lead to the development of numerous alternative pharmacological strategies. This review article outlines the physiological processes occurring in chronic pain, highlights some of the approaches recently developed and mentions a number of drugs currently under development that aim to provide safer and more effective analgesia for chronic pain. These include COX-2 inhibitors, gabapentin, capsaicin, new opioid strategies, neurokinin-1 (NK-1) antagonists, cannabinoid receptor agonists, neuronal nitric oxide synthase (nNOS) inhibitors and NMDA receptor antagonists, as well as a number of other therapeutic strategies in development.

• δ opioid receptor agonists
• adenosine kinase inhibitors
• AMPA receptor antagonists
• bradykinin receptor antagonists
• cannabinoid receptor agonists
• capsaicin
• cholinergic receptor agonists
• chronic pain
• COX-2 inhibitors
• gabapentin
• N-type calcium channel blockers
• NGF receptor antagonists
• NK-1 receptor antagonists
• NMDA receptor antagonists
• NOS inhibitors
• P2X receptor antagonists
• somatostatin analogues
• therapeutic targets
• TTXi receptor antagonists
• VR-1 receptor agonists