title: Effects of a single bolus intravenous dose of tramadol on minimum alveolar concentration (MAC) of sevoflurane in dogs.
abstract: Tramadol is an atypical opioid analgesic widely used in small animal practice. This study was designed to determine the effect of a single intravenous (IV) dose of tramadol on the minimum alveolar concentration (MAC) of sevoflurane in dogs. Six beagle dogs were anesthetized twice to determine the sevoflurane MAC with or without an administration of tramadol (4 mg/kg, IV) at 7 days interval. The sevoflurane MAC was determined using a tail clamp method in each dog ventilated with positive pressure ventilation. The tramadol administration produced a significant reduction in the sevoflurane MAC by 22.3 ± 12.2% (1.44 ± 0.28% with tramadol versus 1.86 ± 0.30% without tramadol, P=0.010). This MAC reduction had been determined from 122 ± 19 to 180 ± 41 min following the tramadol administration. During this period, the plasma concentrations of tramadol and its metabolite, O-desmethyltramadol (M1), decreased from 429 ± 64 to 332 ± 55 ng/ml and from 136 ± 24 to 114 ± 68 ng/ml, respectively, but these changes were not statistically significant. There was no significant difference in heart rate, mean arterial blood pressure and SpO2 between the control and tramadol treatment. The dogs that received tramadol treatment sometimes breathed spontaneously. Therefore, their respiratory rates significantly increased, and PETCO2 decreased during the MAC determination. In conclusion, the single IV dose of tramadol produced a significant reduction in the sevoflurane MAC in dogs.
authors.affiliation: Department of Small Animal Clinical Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan.
authors.forename: Takaharu
authors.initials: T
authors.lastname: Itami
authors.forename: Kodai
authors.initials: K
authors.lastname: Kawase
authors.forename: Naomichi
authors.initials: N
authors.lastname: Tamaru
authors.forename: Tomohito
authors.initials: T
authors.lastname: Ishizuka
authors.forename: Jun
authors.initials: J
authors.lastname: Tamura
authors.forename: Kenjirou
authors.initials: K
authors.lastname: Miyoshi
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Umar
authors.forename: Hiroki
authors.initials: H
authors.lastname: Inoue
authors.forename: Kazuto
authors.initials: K
authors.lastname: Yamashita
mesh_terms: D000704:Analysis of Variance; D018685:Anesthetics, Inhalation / Q000032:analysis*; D000818:Animals; D004285:Dogs; D005260:Female; D007275:Injections, Intravenous / Q000662:veterinary; D008297:Male; D008738:Methyl Ethers / Q000032:analysis*; D011175:Positive-Pressure Respiration / Q000662:veterinary; D011650:Pulmonary Alveoli / Q000378:metabolism*; D056152:Respiratory Rate / Q000187:drug effects; D000077149:Sevoflurane; D014147:Tramadol / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D014147:Tramadol