The N-methyl-D-aspartate receptor antagonist dextromethorphan selectively reduces temporal summation of second pain in man.
Oral doses of dextromethorphan (DM), a common cough suppressant and N-methyl-D-aspartate (NMDA) receptor antagonist, and their vehicle control were given on a double-blind basis to normal volunteer human subjects who rated intensities of first and second pain in response to repeated painful electric shocks and repeated 52 degrees C heat pulses. Doses of 30 and 45 mg, but not 15 mg, were effective in attenuating temporal summation of second pain, a psychophysical correlate of temporal summation of C afferent-mediated responses of dorsal horn nociceptive neurons, termed 'wind-up'. By contrast, neither first nor second pain evoked by the first stimulus in a train of stimuli were affected by any of these doses of DM. These results further confirm temporal summation of second pain as a psychophysical correlate of wind-up by providing evidence that DM selectively reduces temporal summation of second pain, as has been shown for wind-up.
Price
Donald D
DD
Department of Anesthesiology, Medical College of Virginia, Virginia Commonwealth University, MCV Station, Richmond, VA 23298 USA.
Mao
Jianren
J
Frenk
Hanan
H
Mayer
David J
DJ
D000328:Adult; D003915:Dextromethorphan / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004558:Electric Stimulation; D004594:Electrophysiology; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology; D009619:Nociceptors / Q000187:drug effects; D010146:Pain / Q000188:drug therapy* / Q000503:physiopathology; D010147:Pain Measurement / Q000187:drug effects; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*
D016194:Receptors, N-Methyl-D-Aspartate; D003915:Dextromethorphan