Methadone Dose Conversion Guidelines
Timothy Quill M.D. and Nicole Kuderer M.D.
Palliative Care Program - University of Rochester Medical Center
Advantages: Potency, infrequent dosing, effect on neuropathic pain, usable in renal failure, low cost
Disadvantages: Variable t ½, can accumulate with high doses, difficult equianalgesic conversion
Direct Morphine-Methadone Conversion *
24 hour total dose of oral morphine Conversion ration oral morphine to oral methadone
• < 30 mg * 2:1 (2 mg morphine to 1 mg methadone)
• 31-99 mg * 4:1
• 100-299 mg * 8:1
• 300-499 mg * 12:1
• 500-999 mg * 15:1
• >1000 mg * 20:1
(*Fisch and Cleeland. Managing Cancer Pain in Skeel ed. Handbook of Cancer Chemotherapy. 6
th
ed., Phil, Lippincott, 2003, p 663)
Some caveats:
• Give q 6h first day for faster onset, and then BID or TID in divided doses
• Use added caution in higher doses, as half life may increase even further
• Always advise to “hold dose for sedation”
• Generally don’t increase daily dose more often than q 4-7 days
• Remember, small dose changes can have major effect on blood level
• Initial doses should never exceed 240 mg methadone per day; if you are approaching this dose,
consider giving 30 mg q 3 h prn, hold for sedation
• Increase methadone levels with antivirals, keto or fluconazole, cipro, emycin
• Decrease methadone levels with dilantin, tegretol, steroids, rifampin, chronic etoh
Morphine-Methadone Conversion (Morley-Markin Model)
• Give 10% of the total daily morphine dose q 3h prn (hold for sedation)
• N.B. Dose should never exceed 30 mg q3h prn to start
• Can give an additional 2 doses prn bringing the total daily number of doses to 10
• Day 6, take the average daily dose given over the last 48 hours; give as divided dose BID or TID
Some additional caveats about Morley-Markin:
• Relatively simple, but need very reliable patient/family/staff, as risk of taking too much is high
• Dose calculations at 360 mg oral morphine radically different (MM would be methadone 30 mg q
3h prn; standard conversion would be 30 mg per day!)
What to do about prn’s?
• Maintain short acting medication if you have one that works, or
• Give 1/6 to 1/10 of total daily methadone dose 2-3 times per day maximum
• Remember, small dose changes of methadone have large impact if taken regularly
Methadone to Morphine Conversion
• Minimal data; often difficult given the multiple receptors that methadone affects
• Start with oral methadone: oral morphine of 1:1 to 1:3
• Be prepared to increase dose rapidly
Practical Facts
• Pills 5, 10, 40 mg; Liquid 1mg/cc, 2mg/cc, 10mg/cc; Parenteral 10mg/cc; Parenteral
ral 1:2
• Cost of methadone: 1/10 MS Contin, 1:15 Oxycontin, 1/20 Duragesic
• Get help if converting from large doses of other opioids, if converting to IV, or if inexperienced
Some Key References
1. Gazelle G et al. Methadone for pain: Fast Fact #75. J Palliat Med. 2004;7(2).
2. von Gunten C. Methadone: Starting dosing information: Fast Fact #86. J Palliat Med. 2004;7(2)
3. Bruera E. et al: Methadone use in Cancer Patients with Pain: A Review. Journal of Palliative Medicine 2002;5(1):127-138
4. Bruera E. et al. JCO 2004; 22:185-192 5. Moryl N. et al. Pain 2002; 96:325-328
6. Nicholson AB. et al. Cochrane Library 2003 7. Mellar PD et al. Suort Care Cancer 2001; 9:73-83
8. Mancini I. et al. Current Opinion in Oncology 2000; 12:308-313
9. Mercadante S. et al. Support Care Cancer 2003; 11:3260331 10. Bruera E. et al. JCO 2004; 22:185-192
11. Moryl N. et al. Pain 2002; 96:325-328 12. Mercadante S. et al. JCO 2001; 11:2898-2904
