Information about Methadone to Treat Chronic Pain
(A guideline for nurses. Use this in conjunction with the handout “Methadone Information for Patients & Families” from the Journal of Palliative Medicine)
What is Methadone?
A synthetic opioid narcotic, with a long half-life (only needs to be given two or three times a day), which comes in tablet, liquid, and injectible forms. [the tabs can be crushed and made into a slurry for sublingual use also] It is potent (approx. 10x morphine) and because of its long half-life, must be initiated slowly over several days. There is no “gold standard” method for switching from another narcotic to methadone, but the following has been shown to be safe and effective. A dosage log MUST be kept by the patient/family as well as one by the RN.
Methadone Dosing Protocol when Switching from Another Narcotic
1. Calculate the MEDD (Morphine Equivalent Daily Dose) for the current narcotic (use the Equianalgesic Opioid Chart).
2. Convert the MEDD to Methadone based on the following table:
MEDD (oral) – Conversion Ratio (po morphine: po Methadone)
<30mg/day – 2:1
30-99mg/d – 4:1
100-299mg/d – 8:1
300-499mg/d – 12:1
500-999mg/d – 15:1
1000+ mg/day – 20:1
3. Divide the total daily Methadone dose, from the table above, into Q8h.
4. For breakthrough pain, use 10% of the Methadone starting dose, q3h prn (max. 30mg); or, may use previous morphine, Dilaudid, or oxycodone, until steady state with Methadone achieved [4-5 days].
Once established, how to adjust the daily dose:
If >1 prn dose required every day, may increase scheduled dose by 1/3 to 1/2, no more often than every five days.
Patient taking oxycodone (Percocet 10/325) q4h prn (4 doses/day), and using OxyContin 100mg Q8h.
Oxycodone 10mg x4/day (40mg total) = 64mg morphine equiv. (1.6 x 40)
OxyContin 100mg x3/day (300mg total) = 480mg morphine equiv. (1.6 x 300)
Total morphine equiv./day = 544mg/day
Methadone table conversion (500-999) = 15:1 = 544/15 = 36mg methadone
Therefore, start 10mg tab methadone q8h (10mg is smallest tab); and use 5mg (1/2 tab) q3h prn for breakthrough pain. [dosage is slightly lower than actual calculation, to accommodate tab size and for safety; if used liquid, could be more accurate, but not likely significant.)