title: Effect of Acetaminophen Alone and in Combination with Morphine and Tramadol on the Minimum Alveolar Concentration of Isoflurane in Rats.
abstract: BACKGROUND
  It has been observed that acetaminophen potentiates the analgesic effect of morphine and tramadol in postoperative pain management. Its capacity as an analgesic drug or in combinations thereof to reduce the minimum alveolar concentration (MAC) of inhalational anesthetics represents an objective measure of this effect during general anesthesia. In this study, the effect of acetaminophen with and without morphine or tramadol was evaluated on the isoflurane MAC.
  
  
  METHODS
  Forty-eight male Wistar rats were anesthetized with isoflurane in oxygen. MACISO was determined from alveolar gas samples at the time of tail clamping without the drug, after administering acetaminophen (300 mg/kg), morphine (3 mg/kg), tramadol (10 mg/kg), acetaminophen (300 mg/kg) + morphine (3 mg/kg), and acetaminophen (300 mg/kg) + tramadol (10 mg/kg).
  
  
  RESULTS
  The control and acetaminophen groups did not present statistically significant differences (p = 0.98). The values determined for MACISO after treatment with acetaminophen + morphine, acetaminophen + tramadol, morphine, and tramadol were 0.98% ± 0.04%, 0.99% ± 0.009%, 0.97% ± 0.02%, and 0.99% ± 0.01%, respectively.
  
  
  CONCLUSIONS
  The administration of acetaminophen did not reduce the MAC of isoflurane and did not potentiate the reduction in MACISO by morphine and tramadol in rats, and therefore does not present a sparing effect of morphine or tramadol in rats anesthetized with isoflurane.
authors.affiliation: Faculty of Veterinary Medicine, Department of Anesthesiology, Universidad Autónoma del Estado de México, El Cerrillo Piedras Blancas, Toluca, Estado de México, Mexico.
authors.forename: Julio R
authors.initials: JR
authors.lastname: Chavez
authors.affiliation: Faculty of Veterinary Medicine, Department of Anesthesiology, Universidad Autónoma del Estado de México, El Cerrillo Piedras Blancas, Toluca, Estado de México, Mexico.
authors.forename: José A
authors.initials: JA
authors.lastname: Ibancovichi
authors.affiliation: Faculty of Veterinary Medicine, Department of Pharmacology, Universidad Autónoma del Estado de México, El Cerrillo Piedras Blancas, Toluca, Estado de México, México.
authors.forename: Pedro
authors.initials: P
authors.lastname: Sanchez-Aparicio
authors.affiliation: Faculty of Veterinary Medicine, Universidad Autónoma de Yucatán, Department of Anesthesiology and Pharmacology, Merida, Yucatán, México.
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Acevedo-Arcique
authors.affiliation: Faculty of Veterinary Medicine, Department of Anesthesiology, Universidad Autónoma del Estado de México, El Cerrillo Piedras Blancas, Toluca, Estado de México, Mexico.
authors.forename: Rafael
authors.initials: R
authors.lastname: Moran-Muñoz
authors.affiliation: Faculty of Veterinary Medicine, Department of Pharmacology, Universidad Autónoma del Estado de México, El Cerrillo Piedras Blancas, Toluca, Estado de México, México.
authors.forename: Sergio
authors.initials: S
authors.lastname: Recillas-Morales
mesh_terms: D000082:Acetaminophen / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D015415:Biomarkers; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D007530:Isoflurane / Q000493:pharmacokinetics*; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D011650:Pulmonary Alveoli / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats; D014147:Tramadol / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D015415:Biomarkers; D000082:Acetaminophen; D014147:Tramadol; D009020:Morphine; D007530:Isoflurane