Changes in formalin-evoked spinal Fos expression and nociceptive behaviour after oral administration of Bufferin A (aspirin) and L-5409709 (ibuprofen + caffeine + paracetamol).
This study compares the effects of two non-steroidal anti-inflammatory drugs, Bufferin A (BA) and L-5409709 (L-54), on nociceptive behaviour and spinal Fos expression induced by subcutaneous formalin in the rat. BA contains aspirin. L-54 contains ibuprofen, caffeine and paracetamol. Doses based on the human posology were administered orally 30 or 40 min before subcutaneous intraplantar injection of formalin (1.5%, 50 microl) in the right hindpaw. Low doses (BA, 24 mg/kg; L-54, 21.5 mg/kg) did not significantly affect the behavioural pain response. High doses (BA, 480 mg/kg; L-54, 430 mg/kg) reduced the late phase of the response by 42% and 62% respectively, but did not affect the early phase of the response. No sedative side-effects were observed. The two drugs had different effects on the number of spinal Fos-like immunoreactive neurones 2 h after the formalin injection. Fos expression was reduced after BA treatment, and this reduction was correlated to and matched the reduction of the pain response. In contrast, Fos expression after L-54 treatment was not reduced and was not correlated to the reduction in the pain response. The Fos results reveal clear differences in the way that BA (aspirin) and L-54 (ibuprofen + caffeine + paracetamol) affected transmission of the noxious signal. They suggest that BA did not act beyond the spinal cord and that L-54 had more central sites of action than BA.
Carrive
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School of Psychology, University of New South Wales, Australia. p.carrive@unsw.edu.au
Meyer-Carrive
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D000082:Acetaminophen / Q000494:pharmacology*; D000284:Administration, Oral; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D001241:Aspirin / Q000494:pharmacology*; D002110:Caffeine / Q000494:pharmacology*; D004338:Drug Combinations; D005557:Formaldehyde / Q000494:pharmacology*; D007052:Ibuprofen / Q000494:pharmacology*; D007150:Immunohistochemistry; D008297:Male; D009619:Nociceptors / Q000187:drug effects* / Q000502:physiology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013116:Spinal Cord / Q000378:metabolism*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D004338:Drug Combinations; C106625:L 5409709; D016760:Proto-Oncogene Proteins c-fos; D005557:Formaldehyde; D000082:Acetaminophen; D002110:Caffeine; D001241:Aspirin; D007052:Ibuprofen