Current evidence for central analgesic effects of NSAIDs: an overview of the literature.

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely prescribed for a variety of painful conditions. Their peripheral anti-inflammatory effect due to inhibition of prostaglandin synthesis is well documented. In the late 1980's, animal data suggested for the first time that NSAIDs might have central effects as well. Since that time, central inflammatory and nociceptive pathways that are potential targets of NSAIDs have been extensively studied in both animal and human models. This review provides an overview of the relevant literature implicated in the central effects of NSAIDs. The role of different enzymes and mediators, as well as the central effects of NSAIDs are discussed. Literature search was performed by PubMed NCBI. A large body of evidence supports the central effects of NSAIDs in animal models of inflammatory pain conditions. Relevant mechanisms that underlie this central action involve spinal upregulation of the enzyme cyclooxygenase, increased spinal prostaglandin E2 production, modulation of inhibitory fast synaptic currents in lamina I and II of the dorsal horn, and glycine-dependent modulation of pain. Results from animal models are not yet sufficiently supported by human studies. This does not necessarily imply that the central effects of NSAIDs are irrelevant to human pain, but rather that methodological and regulatory barriers are the limiting step to translating findings from animal studies to human research protocols.