Effects of gabapentin in acute inflammatory pain in humans.
OBJECTIVE
The aim of the study was to examine the analgesic effects of the anticonvulsant, gabapentin, in a validated model of acute inflammatory pain.


METHODS
Twenty-two volunteers were investigated in a double-blind, randomized, placebo-controlled cross-over study. Gabapentin 1,200 mg or placebo was given on 2 separate study days. Three hours after drug administration, a first-degree burn injury was produced on the medial aspect of the nondominant calf (12.5 cm(2), 47 degrees C for 7 minutes). Quantitative sensory testing (QST) included pain ratings to thermal and mechanical stimuli (visual analog scale [VAS]), assessments of thermal and mechanical detection thresholds, and areas of secondary hyperalgesia. Side effects drowsiness and postural instability were assessed by subjective ratings (VAS).


RESULTS
The burn injury induced significant primary and secondary hyperalgesia (P <.0001). Gabapentin diminished the decrease in mechanical pain threshold in the burn area (P =.04) and reduced secondary hyperalgesia, but the reduction was not significant (P =.06). Heat pain thresholds, pain during the burn, and mechanical pain in the area of secondary hyperalgesia were not significantly changed by gabapentin (P <.2). Ratings of drowsiness and unsteadiness during walking were significantly higher for gabapentin than for placebo (P <.05).


CONCLUSIONS
The study indicates that gabapentin has no analgesic effect in normal skin, but may reduce primary mechanical allodynia in acute inflammation following a thermal injury. These observations suggest a clinical potential of gabapentin in the treatment of postoperative pain.
Werner
M U
MU
Acute Pain Service, Department of Anesthesiology, Hvidovre University Hospital, Copenhagen, Denmark. madswerner@medscape.com
Perkins
F M
FM
Holte
K
K
Pedersen
J L
JL
Kehlet
H
H
D000085:Acetates / Q000627:therapeutic use*; D000208:Acute Disease; D000328:Adult; D000588:Amines; D000700:Analgesics / Q000627:therapeutic use*; D018592:Cross-Over Studies; D003509:Cyclohexanecarboxylic Acids; D004311:Double-Blind Method; D000077206:Gabapentin; D006801:Humans; D007249:Inflammation / Q000188:drug therapy*; D008297:Male; D010146:Pain / Q000188:drug therapy*; D017288:Pain Threshold / Q000187:drug effects; D005680:gamma-Aminobutyric Acid
D000085:Acetates; D000588:Amines; D000700:Analgesics; D003509:Cyclohexanecarboxylic Acids; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin