NMDA receptor blockade in chronic neuropathic pain: a comparison of ketamine and magnesium chloride.
Ten patients (4 female, 6 male) aged 34-67 years suffering from peripheral neuropathic pain participated in a double-blind placebo-controlled study where ketamine or magnesium chloride were administered by a 10 min bolus infusion (ketamine: 0.84 mumol/kg = 0.2 mg/kg, magnesium: 0.16 mmol/kg) followed by a continuous infusion (ketamine: 1.3 mumol/kg/h = 0.3 mg/kg/h, magnesium: 0.16 mmol/kg/h). Ongoing pain determined by VAS score, area of touch-evoked allodynia, detection and pain thresholds to mechanical and thermal stimuli were measured before and during drug infusion. Ketamine produced a significant reduction of spontaneous pain (57%) and of the area of allodynia (33%). Magnesium chloride reduced pain (29%) and area of allodynia (18%) insignificantly. Following ketamine there was a significant correlation between the reduction in ongoing pain and reduction in area of touch-evoked allodynia. Detection and pain thresholds to mechanical and thermal stimuli were not significantly changed by the drugs. These findings suggest that both ongoing pain and touch-evoked pain (allodynia) in neuropathic pain are inter-related phenomena, which may be mediated by the same mechanism and involving a N-methyl-D-aspartate receptor.
Felsby
S
S
Department of Neurology, Aarhus University Hospital, and Pain Research Center, Aarhus University, DK-8000 Aarhus C Denmark Laboratory of Experimental Pain Research, Aalborg University, DK-9000 Aalborg Denmark Department of Anaesthesiology, Aarhus Amtssygehus, Aarhus University Hospital, DK-8000 Aarhus C Denmark.
Nielsen
J
J
Arendt-Nielsen
L
L
Jensen
T S
TS
D000328:Adult; D000368:Aged; D000778:Anesthetics, Dissociative / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D002908:Chronic Disease; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000188:drug therapy; D007649:Ketamine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D015636:Magnesium Chloride / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000188:drug therapy* / Q000209:etiology / Q000523:psychology; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects; D010523:Peripheral Nervous System Diseases / Q000150:complications*; D010812:Physical Stimulation; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*
D000778:Anesthetics, Dissociative; D016194:Receptors, N-Methyl-D-Aspartate; D015636:Magnesium Chloride; D007649:Ketamine