TABLE 4

Weaning Protocols by Using Conversion of Continuous Opioid Infusions to Enteral Methadone and for Conversion of Midazolam (Versed) Infusion to Enteral Lorazepam (Ativan)

Robertson et al149
Conversion of continuous intravenous fentanyl of 7–14 d duration to enteral methadone:
 1. By using the current hourly infusion rate, calculate the 24-h fentanyl dose.
 2. Multiply the daily fentanyl dose by a factor of 100 to calculate the equipotent amount of methadone (ratio of potencies assumed to be fentanyl: methadone = 100:1).
 3. Divide this amount of methadone by 6 (a correction for the longer half-life of methadone) to calculate an initial total daily dose of methadone, and on day 1 provide this amount orally in 4 divided doses every 6 h for 24 h.
 4. Day 2: Provide 80% of original daily dose in 3 divided oral doses every 8 h for 24 h.
 5. Day 3: Provide 60% of original daily dose in 3 divided oral doses every 8 h for 24 h.
 6. Day 4: Provide 40% of original daily dose in 2 divided oral doses every 12 h for 24 h.
 7. Day 5: Provide 20% of original daily dose × 1.
 8. Day 6: Discontinue methadone.
Conversion of continuous intravenous fentanyl greater than 14 d duration to enteral methadone:
 1. Repeat steps 1–2 above.
 2. Days 1–2: Divide the dose of methadone by 6 (a correction for the longer half-life of methadone) and on day 1 provide this amount orally in 4 divided doses every 6 h for 48 h.
 3. Days 3–4: Provide 80% of original daily dose in 3 divided oral doses every 8 h for 48 h.
 4. Days 5–6: Provide 60% of original daily dose in 3 divided oral doses every 8 h for 48 h.
 5. Days 7–8: Provide 40% of original daily dose in 2 divided oral doses every 12 h for 48 h.
 6. Days 9–10: Provide 20% of original daily dose once per day for 48 h.
 7. Day 11: Discontinue methadone.
For patients on continuous intravenous morphine, proceed as above but do not multiply the daily fentanyl dose by 100, because morphine and methadone are nearly equipotent.
Meyer and Berens150
Conversion of continuous intravenous fentanyl to intermittent intravenous morphine:
 1. By using the target hourly infusion rate of fentanyl, calculate the 24-h fentanyl dose.
 2. Multiply the daily fentanyl dose by a factor of 60 to calculate the equipotent dose of morphine (ratio of potencies assumed to be fentanyl: morphine = 60:1).
 3. Divide the dose of morphine by 4 (correcting for the longer half-life of morphine) and on day 1 administer this amount intravenously in 6 divided doses every 4 h.
 4. Titrate the morphine dose for adequate effect over 12 to 24 h.
Conversion of intermittent intravenous morphine to enteral methadone:
 1. Multiply the dose of morphine given every 4 h by 2 (ratio of potencies assumed to be morphine: methadone = 2:1) to determine an equipotent amount of methadone.
 2. Provide this amount of methadone as an oral dose every 12 h for 3 doses.
 3. Double this amount of methadone and provide as a single oral dose per day at bedtime.
 4. Provide 90% of the initial dose on day 2, 80% on day 3, etc, so that the last dose of methadone (10% of the original dose) is given on day 10.
Protocols at Wolfson Children’s Hospital, Jacksonville, Florida
Conversion of continuous intravenous fentanyl >7 d duration to enteral methadone:
 1. By using the current hourly infusion rate, calculate the 24-h fentanyl dose.
 2. Multiply the daily fentanyl dose by a factor of 100 to calculate the equipotent amount of methadone (ratio of potencies assumed to be fentanyl: methadone = 100:1).
 3. Divide this amount of methadone by 8–12 (a correction for the longer half-life of methadone) to calculate an initial total daily dose of methadone (not to exceed 40 mg/day).
 4. Days 1–2: Provide the total daily dose of methadone orally in 4 divided doses every 6 h for 48 h. At the time of the second methadone dose, reduce the fentanyl infusion rate to 50%; at the time of the third dose, reduce the fentanyl infusion rate to 25%; and after the fourth methadone dose, discontinue the fentanyl infusion.
 5. Days 3–4: Provide 80% of original daily dose in 3 divided oral doses every 8 h for 48 h.
 6. Days 5–6: Provide 60% of original daily dose in 3 divided oral doses every 8 h for 48 h.
 7. Days 7–8: Provide 40% of original daily dose in 2 divided oral doses every 12 h for 48 h.
 8. Days 9–10: Provide 20% of original daily dose once per day for 48 h.
 9. Day 11: Discontinue methadone.
Conversion of continuous intravenous midazolam >7 d duration to enteral lorazepam:
 1. By using the current hourly infusion rate, calculate the 24-h midazolam dose.
 2. Because lorazepam is twice as potent as midazolam and has a sixfold longer half-life, divide the 24 h midazolam dose by 12 to determine the daily lorazepam dose.
 3. Divide the calculated lorazepam dose by 4 and initiate every 6 h oral treatments with the intravenous product or an aliquot of a crushed tablet.
 4. Wean lorazepam by 10% to 20% per day. The dosage interval can also be increased gradually to every 8 h, then every 12 h, then every 24 h, and then every other day before lorazepam is discontinued.
Summary of Conversion Of Intravenous Opioids to Enteral Methadone
 1. Tobias et al147: Converted 2 patients on morphine (0.1–0.15 mg/kg q3h) and 1 patient on fentanyl (1–2 µg/kg every 1–2 h) to methadone at a starting dose of 0.2 mg/kg per day.
 2. Robertson et al149: 1 µg/kg per h fentanyl = 0.4 mg/kg per day methadone.
 3. Meyer and Berens150: 1 µg/kg per h fentanyl = 0.24 mg/kg per day methadone.
 4. Wolfson Children’s Hospital: 1 µg/kg per h fentanyl = 0.2–0.3 mg/kg per day methadone.