Opioid conversion

MME (risk): CDC 2022 conversion factors × total daily dose. CDC states these must not be used to convert one opioid to another. The new opioid is usually dosed well below the calculated MME, because cross-tolerance is incomplete and pharmacokinetics vary.

CDC lists no parenteral factors. For IV/SC morphine and hydromorphone the tool reports an oral-morphine equivalent from the equianalgesic table below, flagged †.

Rotation: the McPherson 2018 (ASHP) equianalgesic table, used for the rotation arithmetic only.

New 24-h dose = Σ (current 24-h dose ÷ table dose of current drug/route) × table dose of new drug/route Starting dose = new 24-h dose × (1 − reduction) → ÷ doses per day → rounded DOWN to available strengths Breakthrough dose = 10–20% of the new scheduled 24-h dose, rounded down

The two tables disagree on purpose (oxycodone is 1.5 MME but 1.25 by McPherson; tapentadol 0.4 vs 0.25). Equianalgesic tables rest on small, mostly single-dose studies and are not always bidirectional. Hydromorphone → morphine runs about 3.7:1 rather than 5:1, so the table overestimates morphine when going that direction.

• Conversion to methadone: the conversion ratio rises steeply with the prior opioid dose. Fine & Portenoy advise a 75–90% reduction, and CDC 2022 limits methadone to clinicians experienced with its long, variable half-life and QT risk. Rotation from methadone is also blocked (except to the fentanyl patch, which its label lists).
• Buprenorphine: CDC excludes it from the MME table because partial µ-agonism gives ceiling effects. Starting or stopping it needs a specific induction plan.
• From the fentanyl patch: the label says its conversion tables cannot be used in reverse, because they would overestimate the new opioid and may cause fatal overdose. Serum fentanyl falls by about 50% in 20–27 h after removal.
• To the fentanyl patch: only via the label's Table 1 (listed opioids and doses) or Table 2 (oral-morphine ranges). Both are deliberately conservative, so no extra cross-tolerance reduction is applied. Patients must be opioid-tolerant.
  • Above the top of Table 1 for oxycodone, IV morphine, oral or IV hydromorphone, or codeine, the tool stops. Table 1's columns imply about 2:1 for oxycodone and 7.5:1 for oral hydromorphone, while Table 2 needs an equianalgesic reference (McPherson 1.25:1 and 5:1). Switching basis would make the patch dose fall as the dose rises. Oral morphine continues straight into Table 2.
  • Combined regimens use Table 2 with McPherson oral-morphine equivalents. The result is never lower than the Table 1 value of any single listed component.
  • Unreachable Table 1 cells: codeine 150–447 mg/day, IV morphine 10–23.9 mg/day and IV hydromorphone 1.5–4.7 mg/day sit in Table 1's 25 mcg/h column, but they fall below the label's own opioid-tolerance definition (60 mg/day oral-morphine equivalent, using the McPherson table). The patch is contraindicated in non-tolerant patients, so the tool keeps the stricter rule and blocks them.
• Opioid-naïve patients: do not convert. Start at the label's lowest dose; CDC notes that is often 5–10 MME per dose or 20–30 MME/day.
• Hydrocodone, codeine, tramadol or tapentadol as the new drug: not offered. Combination products and ceiling doses make a tablet schedule unsafe to automate. IV fentanyl is not supported.

Column headers are the patch dose in mcg/h. IM meperidine is also listed in the label but is not offered here. Table 2 (oral morphine mg/day → mcg/h): 60–134 → 25; 135–224 → 50; 225–314 → 75; 315–404 → 100; 405–494 → 125; 495–584 → 150; 585–674 → 175; 675–764 → 200; 765–854 → 225; 855–944 → 250; 945–1034 → 275; 1035–1124 → 300. Doses that fall in a gap between rows are assigned to the lower row.

Label rules: opioid-tolerant only — for ≥1 week, at least 60 mg oral morphine, 25 mcg/h fentanyl, 30 mg oxycodone, 8 mg hydromorphone, 25 mg oxymorphone or 60 mg hydrocodone daily, or equivalent. When the patch starts, stop other around-the-clock opioids. First increase no sooner than 3 days, then no more often than every 6 days; step size 12 mcg/h per 45 mg/day oral morphine of rescue use. Mild–moderate hepatic or renal impairment: start at one-half; avoid if severe. Heat and fever (40 °C) raise fentanyl levels about one-third, and CYP3A4 inhibitors can cause fatal overdose.

• MME ≥50/day (CDC 2022): pause and reassess benefit before going higher. At or above 50, increase follow-up and offer naloxone with overdose education. There is no dose below which risk disappears.
• MME ≥90/day: the 2016 CDC guideline said to avoid this or justify it carefully. The 2022 update removed fixed caps but cites overdose risk at ≥100 MME/day of 2.0–8.9× that at 1–<20.
• Renal (CrCl <30 or dialysis): avoid morphine and codeine (MD Anderson Appendix H), so morphine targets are blocked. Tapentadol is not recommended. Tramadol: every 12 h, max 200 mg/day. Patch: avoid in severe impairment.
• Age ≥65, renal or hepatic impairment: CDC 2022 advises extra caution and monitoring because the therapeutic window is narrower.
• Benzodiazepines: CDC 2022 Rec 11 — use particular caution; offer naloxone.
• ER/LA targets are offered only when the opioid-tolerance index is ≥1. This is stricter than some labels: CDC 2022 Rec 3 says ER/LA opioids should be considered only after ≥1 week of daily IR opioids at, e.g., 60 mg oral morphine. Labels limit some products and strengths to opioid-tolerant patients (OxyContin 60/80 mg tablets, single doses >40 mg or >80 mg/day; morphine ER 100/200 mg), while MS Contin may be started at 15 mg every 8–12 h in non-tolerant patients.
• Plausibility stops: each opioid and route has a tool limit, set several multiples above usual practice, for the dose, the hourly rate and the 24-h total. Above it the tool stops with "Check dose/units". Amber flags cite label limits where they exist: codeine 360 mg/day and no added efficacy above 60 mg per dose; tramadol 400 mg/day; tapentadol IR 600 mg/day after day 1; IV morphine starting dose 0.1–0.2 mg/kg every 4 h (morphine sulfate injection label, Fresenius Kabi 2026); IV hydromorphone starting dose 0.2–1 mg every 2–3 h (hydromorphone injection label, Hikma 2026). Suggested IV breakthrough boluses stop at ≥20 mg morphine or ≥4 mg hydromorphone; scheduled IV boluses stop at ≥30 mg or ≥6 mg. MD Anderson's PCA appendix sets the demand dose for opioid-tolerant patients at 10–20% of the new 24-h IV dose, the same rule used here. No sourced cap relative to the hourly infusion rate was found, so none is applied. Calculated new doses, rates and breakthrough doses are checked against the same limits.
• >500 MME/day: results are framed as needing pain or palliative specialist input, not as a regimen to start.