ABSTRACT
Cardiopulmonary and sedative effects of intravenous or epidural methadone were compared. Six beagles were randomly assigned to group MIV (methadone 0.5 mg/kg IV + NaCl 0.9% epidurally) or MEP (methadone 0.5 mg/kg epidurally + NaCl 0.9% IV). Cardiopulmonary, blood gas and sedation were assessed at time (T) 0, 15, 30, 60, 120, 240 and 480 min after drug administration. Compared to T0, heart rate decreased at T15-T120 in MIV (p < .001) and T15-T240 in MEP (p < .05); mean arterial pressure was reduced at T15-T60 in MEP (p < .01); respiratory rate was higher at T15 and T30 in both groups (p < .05); pH was lower at T15-T120 in MIV (p < .01) and T15, T30 and T120 in MEP (p < .05); PaCO2 was higher at T15-T60 in MIV (p < .01) and T15, T30 and T120 in MEP (p < .01); sedation scores were higher at T15 and T30 in MIV and T15-T60 in MEP (p < .05). At T120 and T240, sedation score was higher in group MEP compared with group MIV (p < .01) In conclusion, cardiopulmonary and sedative effects of identical methadone doses are similar when administered IV or epidurally to conscious healthy dogs.
