Pharmacology of peripheral analgesia

Pain may begin in the periphery with activation of nociceptor transducers. The present article reviews the pharmacology of drug action at the level of the primary afferent by discussing the following: [1] agents which block transduction processes (vanilloids, sodium ion channel blockers, antiserotonergic agents, antipurinergic agents); [2] agents inhibiting the transducer site (opioids, cannabinoids, alpha adrenergic agents); [3] agents blocking transducer-based modulation processes (anti-inflammatories, antikinin agents, antitachykinins); and [4] agents which block primary afferent-related modification processes (antineurotrophins). There is a clear role for many of these agents in the treatment of inflammatory pain and they have potential benefits for neuropathic pain with peripheral triggers.