Comparison of the antinociceptive effects of ibuprofen arginate and ibuprofen in rat models of inflammatory and neuropathic pain.
OBJECTIVE
Ibuprofen arginate is a highly soluble salt formed by combining racemic ibuprofen with the amino acid l-arginine. This formulation is absorbed faster, and it is safe and effective in treating many forms of mild to moderate pain. We compared the analgesic effect of ibuprofen arginate and conventional ibuprofen in rat models of pain.


METHODS
Mechanical and cold allodynia were assessed in the chronic constriction injury (CCI) model of neuropathic pain, and mechanical allodynia was also examined in capsaicin-injected rats (a model of central sensitization). Inflammatory hypersensitivity was assessed with the formalin test. Ibuprofen-l-arginine, ibuprofen, l-arginine or saline was administered orally on a daily basis after CCI or capsaicin injection, and the von Frey and cold plate tests were performed on days 1, 3 and 7 after CCI or capsaicin administration. In the formalin-induced inflammatory pain test, the drugs were administered 30 min before formalin injection.


RESULTS
Ibuprofen only exerts an antinociceptive effect in the formalin model whereas ibuprofen-l-arginine exerts antinociceptive effects on both mechanical and cold allodynia induced by CCI, mechanical allodynia induced by capsaicin injection, and in phase 2 of the formalin test, exhibiting superior antinociceptive activity to ibuprofen in all these tests. l-Arginine only exerted antinociceptive effects on cold allodynia in CCI.


CONCLUSIONS
These results demonstrate that ibuprofen arginate has stronger antinociceptive effects than ibuprofen in all the models used, suggesting it might improve the therapeutic management of neuropathic and inflammatory pain.
Research & Development in Neuropsychopharmacology Group (PAI CTS-510), Department of Neuroscience, Faculty of Medicine, University of Cadiz, Cadiz, Spain.
Antonio
A
Ortega-Álvaro
Esther
E
Berrocoso
Raquel
R
Rey-Brea
Juan C
JC
Leza
Juan A
JA
Mico
D018712:Analgesics, Non-Narcotic / Q000627:therapeutic use*; D000818:Animals; D001120:Arginine / Q000627:therapeutic use*; D003080:Cold Temperature / Q000009:adverse effects; D004195:Disease Models, Animal; D004338:Drug Combinations; D007052:Ibuprofen / Q000627:therapeutic use*; D007249:Inflammation / Q000188:drug therapy / Q000473:pathology; D008297:Male; D009437:Neuralgia / Q000188:drug therapy* / Q000473:pathology; D010812:Physical Stimulation / Q000009:adverse effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D020426:Sciatic Neuropathy / Q000188:drug therapy* / Q000473:pathology
D018712:Analgesics, Non-Narcotic; D004338:Drug Combinations; D001120:Arginine; D007052:Ibuprofen; C106674:ibuprofen arginine