Meloxicam, a specific COX-2 inhibitor, does not enhance the isoflurane minimum alveolar concentration reduction produced by morphine in the rat.
A synergistic effect of nonselective cyclooxygenase (COX) inhibitors on morphine-induced decrease of isoflurane minimum alveolar concentration (MAC(ISO)) has been observed in the rat. We studied the influence of specific COX-2 inhibitors on this decrease of MAC. Sixty-four female rats were anesthetized with isoflurane in oxygen. The animals were grouped into saline solution, aspirin (30 mg/kg), morphine (1 mg/kg), morphine (1 mg/kg) + aspirin (30 mg/kg), meloxicam (1 and 3 mg/kg), and morphine (1 mg/kg) + meloxicam (1 and 3 mg/kg). Then the MAC(ISO) was determined from alveolar gas samples at the time of tail clamp. The groups treated with saline solution, aspirin, and 1 and 3 mg/kg meloxicam did not express any statistically relevant changes among them. The administration of morphine + meloxicam 1 or 3 mg/kg significantly reduced the MAC(ISO) just as in the group where only morphine was administered (morphine 1.35% +/- 0.07%, morphine + 1 mg/kg meloxicam 1.36% +/- 0.04%, and morphine + 3 mg/kg meloxicam 1.37% +/- 0.08%). The greatest reduction of MAC(ISO) was after administration of morphine + aspirin (1.19% +/- 0.05%). The administration of meloxicam does not potentiate the morphine-induced decrease of MAC(ISO) in the rat.


CONCLUSIONS
A synergistic effect between morphine and aspirin on isoflurane minimum alveolar concentration has been observed in the rat--an effect that does not occur between morphine and meloxicam.
Santos
Martín
M
From the Servicio de Cirugía Experimental, Hospital Universitario Puerta de Hierro, Madrid, Spain.
Kunkar
Viviana
V
García-Iturralde
Palma
P
Tendillo
Francisco J
FJ
D000701:Analgesics, Opioid / Q000494:pharmacology*; D018685:Anesthetics, Inhalation / Q000493:pharmacokinetics / Q000494:pharmacology*; D000818:Animals; D001241:Aspirin / Q000494:pharmacology; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D004347:Drug Interactions; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007527:Isoenzymes / Q000378:metabolism*; D007530:Isoflurane / Q000493:pharmacokinetics / Q000494:pharmacology*; D000077239:Meloxicam; D009020:Morphine / Q000494:pharmacology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013843:Thiazines / Q000494:pharmacology*; D013844:Thiazoles / Q000494:pharmacology*
D000701:Analgesics, Opioid; D018685:Anesthetics, Inhalation; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D013843:Thiazines; D013844:Thiazoles; D009020:Morphine; D007530:Isoflurane; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D001241:Aspirin; D000077239:Meloxicam