Effects of methadone on the minimum alveolar concentration of isoflurane in dogs

Methadone reduces ISOMAC in a dose-related fashion and this effect is lessened over time. Although the isoflurane sparing effect of the 0.5 mg kg−1 dose of methadone was smaller in comparison to the 1.0 mg kg−1 dose, the lower dose is recommended for clinical use because it results in less evidence of cardiovascular impairment.