Еквіанальгетичні дози опіоїдних анальгетиків*,†

* Equivalences are based on single-dose studies influenced by clinical experience. Cross-tolerance between drugs is incomplete, so when one drug is substituted for another, the equianalgesic dose should be reduced by 50%; methadone should be reduced by 75–90%. Some experts have suggested that morphine:methadone equivalence is nonlinear and that it changes when morphine dosage is higher, as in the following morphine-to-methadone conversion ratios:

• < 30 OMME/day: 2:1

• 31–99 OMME/day: 4:1

• 100–299 OMME/day: 8:1

• 300–499 OMME/day: 12:1

• 500–999 OMME/day: 15:1

• ≥ 1000 OMME/day: 20:1

Methadone dosage should still be reduced by 75–90% even when this more conservative equivalence calculation is used.

† See also Kreutzwiser D, Tawfic QA and Pain Guidelines (based on Quill TE: Primer of Palliative Care, ed. 7. Chicago, Academy of Hospice and Palliative Medicine, 2019).

‡ Parental oxycodone is available in Europe but not in the US.

OMME = oral morphine milligram equivalents.