Drug Discovery and Neuropathic Pain

Pain is one of the most common causes of physician visits and disability. Pain has been classified into specific subtypes. We refer to baseline or nociceptive pain as pain that results from an ongoing, high-threshold stimulus acting on an unenhanced somatosensory system. Inflammatory pain refers to pain in the setting of tissue damage and specifically the release of inflammatory molecules that activate and sensitize the nociceptive machinery. Hyperalgesia, or increased pain in response to a noxious stimulus, results from nociceptor sensitization whereas neuropathic pain results from a lesion or disease of the somatosensory system. Pain can have spontaneous, stimulus-independent components as well as evoked components such as hyperalgesia or allodynia, pain that is elicited by a normally innocuous stimulus. This chapter describes the research strategy for discovering new drugs to relieve these different kinds of pain.