title: Gabapentin and pregabalin can interact synergistically with naproxen to produce antihyperalgesia.
abstract: BACKGROUND
  Gabapentin and pregabalin are anticonvulsants with antihyperalgesic effects in animal models of neuropathic and inflammatory nociception. This study characterized the manner in which gabapentin or pregabalin interacts with naproxen to suppress thermal hyperalgesia and inflammation in the carrageenan model of peripheral inflammation.
  
  
  METHODS
  Gabapentin, pregabalin, naproxen, or a fixed-dose ratio of gabapentin + naproxen or pregabalin + naproxen was administered orally to rats after the induction of inflammation by intraplantar injection of lambda-carrageenan in one hind paw. Nociceptive thresholds were determined by the radiant heat paw-withdrawal test. Paw edema was measured by plethysmometry. Drug plasma concentrations were determined by a liquid chromatography-mass spectroscopy-mass spectroscopy method.
  
  
  RESULTS
  Gabapentin, pregabalin, and naproxen alone reversed thermal hyperalgesia with ED50 values of 19.2, 6.0, and 0.5 mg/kg, respectively. Mixtures of gabapentin + naproxen in fixed-dose ratios of 50:1, 10:1, or 1:1 interacted synergistically to reverse carrageenan-induced thermal hyperalgesia. However, 1:50 gabapentin + naproxen produced only additive effects. No combination of gabapentin + naproxen decreased paw edema in a manner greater than additive. Plasma concentrations of gabapentin and naproxen were unaltered by the addition of the other drug. The mixture of 10:1 of pregabalin + naproxen interacted synergistically to reverse thermal hyperalgesia on the inflamed hind paw, whereas mixtures of 1:1 or 1:10 produced additive effects.
  
  
  CONCLUSIONS
  These data suggest that gabapentin + naproxen and pregabalin + naproxen can interact synergistically or additively to reverse thermal hyperalgesia associated with peripheral inflammation. Therefore, the use of gabapentin or pregabalin in low-dose combinations with naproxen may afford therapeutic advantages for clinical treatment of persistent inflammatory pain.
authors.affiliation: Department of Anesthesia and Critical Care, and Committee on Neurobiology, University of Chicago, Illinois, USA.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Hurley
authors.forename: Debika
authors.initials: D
authors.lastname: Chatterjea
authors.forename: Meihua
authors.initials: M
authors.lastname: Rose Feng
authors.forename: Charles P
authors.initials: CP
authors.lastname: Taylor
authors.forename: Donna L
authors.initials: DL
authors.lastname: Hammond
mesh_terms: D000085:Acetates / Q000097:blood / Q000494:pharmacology*; D000588:Amines; D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects; D003509:Cyclohexanecarboxylic Acids; D004357:Drug Synergism; D000077206:Gabapentin; D006930:Hyperalgesia / Q000188:drug therapy*; D008297:Male; D009288:Naproxen / Q000097:blood / Q000494:pharmacology*; D000069583:Pregabalin; D051381:Rats; D017207:Rats, Sprague-Dawley; D005680:gamma-Aminobutyric Acid / Q000031:analogs & derivatives* / Q000494:pharmacology*
chemical_list: D000085:Acetates; D000588:Amines; D000700:Analgesics; D000894:Anti-Inflammatory Agents, Non-Steroidal; D015220:Calcium Channels; D003509:Cyclohexanecarboxylic Acids; D000069583:Pregabalin; D005680:gamma-Aminobutyric Acid; D009288:Naproxen; D000077206:Gabapentin; D002118:Calcium