Opioid breakthrough dose cheat sheet

Hover (or tap, on a phone) a basal regimen to see the matching PRN breakthrough doses at the same equianalgesic level. The breakthrough dose is usually 10–20 % of the total daily long-acting dose. Click a row to pin it.

	Medication	Level 1	Level 2	Level 3	Level 4	Level 5

Basal rows are blue, PRN rows are pink. Hovering highlights the column (equianalgesic level) and the row; the hovered cell is green.

Equianalgesic doses are approximations aligned to the MMMC formulary, not exact conversions. PRN doses are given every 2–4 hours. Always individualise for renal/hepatic function, age, opioid tolerance and sedation; reassess frequently.

Methadone: deliberately not in the table

Methadone is not a first-line or PRN opioid here, and the levels above must not be used to convert to it. Its potency relative to morphine rises with the prior opioid dose, so there is no fixed ratio; it accumulates for 5–7 days after each dose change; and it prolongs the QTc. Starting methadone or converting to it: involve the pain / palliative service or pharmacy.

Patients already on methadone (opioid treatment program or chronic pain) are a different situation:

Verify the dose and the date and time of the last dose with the dispensing clinic. Clinic-dispensed doses usually do not show in the PDMP. Continue the verified dose; do not stop or taper it during an acute illness.
It does not cover acute pain. A once-daily treatment dose prevents withdrawal but gives only about 6–8 hours of analgesia. Treat pain with short-acting opioids from the PRN rows on top of the methadone, expecting higher and more frequent doses than in an opioid-naive patient because of tolerance; titrate with monitoring.
Avoid mixed agonist-antagonists (nalbuphine, butorphanol); they can precipitate withdrawal.
NPO: ask pharmacy or the pain service for the IV conversion; IV methadone is more potent than oral.
Safety: baseline ECG for QTc; many interactions (azole antifungals, macrolides and other CYP3A4 inhibitors raise levels; rifampin and some antiretrovirals lower them); check other QT-prolonging drugs.
At discharge, tell the clinic which doses were given in hospital and when the last one was.