Conversion from prolonged intravenous fentanyl infusion to enteral methadone in critically ill children

Table 4 Example of dose conversion from intravenous fentanyl infusion directly to enteral methadone

A 10-kg child is receiving IV fentanyl infusion of 5 mcg/kg per hour. The total daily fentanyl dose is 5 μg/kg per hour × 24 h = 1.2 mg/d

Dose conversion ratio - methadone:fentanyl = 2.5 (rounded up from 2.3 observed in rapid conversion group in the present study that converted from IV fentanyl infusion directly to enteral methadone within 48 h) based on potency, half-life and enteral bioavailability

Total daily dose of enteral methadone = 2.5 × 1.2 mg/d = 3 mg/d administered in 2 divided doses, i.e., 1.5 mg dosed every 12 h

Following the second dose of enteral methadone, the IV fentanyl infusion is decreased by 50% to 2.5 mcg/kg per hour

Following the third dose of enteral methadone, the IV fentanyl infusion is decreased again by 50% to 1.25 mcg/kg per hour

Following the fourth dose of enteral methadone, the IV fentanyl infusion is discontinued

IV: Intravenous.