Novel treatments for pain.

At present, the principal treatments for pain are non-steroidal anti-inflammatory drugs (NSAIDs) and opioids, but both of these classes suffer from drawbacks in clinical use. Some of the NSAIDs are associated with gastric damage as well as kidney and liver toxicity, and an increase in blood clotting time, while the opioids can produce tolerance and dependence, along with constipation, nausea, respiratory depression and sedation. In certain cases, both NSAID and opioid use are ineffective. There are some other less commonly used treatments including local anesthetics, anticonvulsants and tricyclic antidepressants, but, many recent strategies have involved the search for other NSAIDs and opioids which lack the unwanted side-effects present in both classes of drug. More recently, in addition to the classical strategies, some novel approaches have started to produce compounds which have entered the clinic, including cyclooxygenase-2 (COX-2) inhibitors and modulators of the alpha2delta subunit of L-type calcium channels.