Module 2: Basic Pharmacology of Controlled Drugs and Substances

Lesson 4

Opioid rotation

Because of the potential for sedative and psychotomimetic actions of opioid agents, it is important to calculate the morphine equivalency of prescribed opioid agents when initially prescribing an opioid as well as when changing the dose or type of opioid. The table below is an example of an opioid equivalency table that may be a useful tool in calculating opioid dosing and supporting decisions when opioid rotation is necessary. Remember that these ratios are estimates, with evidence suggesting that the new opioid should be initiated at a lower dose and titrated up until therapeutic and adverse effects can be observed (NOUGG, 2017; CDC, 2016).

Appendix B-8.1 of the Canadian Guideline for Safe and Effective Use of Opioids for Chronic Non-Cancer Pain (NOUGG, 2017) contains an oral morphine conversion table as well as conversions from oral morphine to transdermal fentanyl.