The 'Opioid Square': A New Way to Learn Opioid Conversions

Topic: Education


We evaluated the “Opioid Square” in comparison to a classic conversion table in a single 2nd year medical school class, assessing both accuracy in making opioid conversions and preference for each tool.

  1. Determine the degree to which the “Opioid Square” tool assists 2nd year medical students to correctly calculate opioid conversions 
  2. Evaluate 2nd year medical student’s preference to use the “Opioid Square” in comparison to the classic equianalgesic tables to calculate opioid conversions. 

Background: Equianalgesic conversions between opioid drugs and oral and intravenous formulations are a clinically important skill for all practitioners who treat pain.  Accuracy is critical to preventing serious adverse events.  Opioid conversion tables are a commonly used tool for teaching this skill, however needs assessment at our institution reveals the classic conversion table is difficult for learners to understand.  A novel visual tool, the "Opioid Square" was developed to provide a different visual framework for opioid conversions.

Methods: The sample consisted of 200  students at a single academic institution who were learning opioid conversions for the first time during their Pharmacology class.  Students were taught conversion using both the standard conversion table, and the "Opioid Square" method.  An eight item conversion quiz followed, on various opioid drugs and formulations of each.  Students were allowed to use either tool and preferences were assessed with qualitative comments. 

Results: 187/200 students participated in the study.  Accuracy of the eight conversion questions was generally good (85-100% correct), and without any statistical differences in accuracy between the  Square and the Table.  Incorrect conversions were more likely on two-step problems (i.e.: IV fentanyl to oral morphine).  A slight majority of students (53%) indicated  that they preferred the Opioid Square over the Conversion Table, and 35% noted they would prefer to use both tools if given the option in the future. 

Conclusions: The novel “Opioid Square” tool is not inferior to the classic opioid equianalgesic table for helping students make accurate conversions.  As many students preferred the "Square," this tool may provide educators with an alternative visual framework for teaching opioid conversions.  Our poster will provide education on using this tool at any institution, and pocket cards will be provided.

A link to the "Opioid Square" tool is found here:


  • Heidi Young, MD
  • Assistant Professor
  • Georgetown University Hospital
  • 3800 Reservoir Rd NW, 6PHC
  • Washington, DC 20007
  • (855) 633-0364


  • Heidi Young, MD
  • James Shear
  • Peggy Compton
  • Yvonne Hernandez

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