Analgesia & Opioid Equivalence
Every analgesia & opioid equivalence calculator on CalcEngines — unit converters, derived indices and interpretive tools, each with its formula, a worked example and the reference intervals it is judged against.
8 calculators in this section
- Buprenorphine Conversion Considerations InterpreterBuprenorphine does not fit an equianalgesic table: it is a high-affinity partial agonist with a ceiling on respiratory depression that can displace a full agonist and precipitate withdrawal. This page says what decides the answer instead of inventing a ratio.
- Codeine and Tramadol CYP2D6 Conversion InterpreterCodeine and tramadol are prodrugs activated by CYP2D6, so a fixed oral morphine equivalent factor is wrong in both tails — far too low in an ultrarapid metaboliser and far too high in a poor one. This page reads the published factor against the CPIC phenotype.
- Fentanyl Patch to Oral Morphine Conversion CalculatorA fentanyl patch rate expressed as oral morphine a day by the published single factor and by both of the manufacturer's bands — which are 2.49-fold apart, and which the Summary of Product Characteristics says must only be read in the other direction.
- Methadone Conversion Dose Bands InterpreterMethadone's conversion factor is not a constant: it rises with the dose. This page prints the four dose-banded factors from CDC's own conversion file against the single factor its 2022 guideline replaced them with, and refuses the direction that is specialist practice.
- Morphine Milligram Equivalent (MME) CalculatorMorphine milligram equivalents by CDC's 2022 factors and by its own pre-2022 factors side by side, because the two disagree by up to 2.55-fold — and MME is a surveillance construct that CDC itself says must not be used to convert one opioid to another.
- Opioid Rotation and Cross-Tolerance CalculatorThe arithmetic equivalent of one oral opioid in another, then the published reduction for incomplete cross-tolerance applied on top of it — with the measured ratios that show the conversion is not the same in both directions.
- Oral Morphine Equivalent Dose CalculatorConvert a 24-hour oral opioid dose to an oral morphine equivalent by four published factor sets at once, with the spread between them shown — because the published factors disagree by up to twofold on the same drug, and the figure is an arithmetic equivalence rather than a dose.
- Oral to Parenteral Opioid Ratio CalculatorThe parenteral equivalent of an oral opioid dose by both published divisors at once — because oral morphine is divided by 2 in some sources and 3 in others, and because the product label's figure for converting back does not return the dose you began with.