Prescribing Opioids to Older Adults: A Guide to Choosing and Switching Among Them

Marc Ginsburg, RN, MScN, NP; Shawna Silver, MD, PEng; Hershl Berman, MD, FRCPC


Geriatrics and Aging. 2009;12(1):48-52. 

In This Article

Converting Between Opioids

When switching between opioids, the goal is to achieve an equianalgesic effect. Equianalgesic conversion tables are based on opioid-naïve patients with acute pain.[19] Table 4 provides an example of equivalent dosing for the commonly chosen drugs.[20] A number of factors must be taken into account when making the switch. In general, to switch between opioids, a rough estimation of the 24-hour dose should be calculated, converted to the new opioid, and then divided by the desired dosing schedule.[20]

Incomplete Cross-tolerance

A patient who has been taking an opioid for an extended period of time may develop a degree of tolerance to it; however, when converting to another opioid, only a part of this tolerance may carry over to the new drug.[9] Therefore, after calculating the required dose of the new drug to achieve an equianalgesic effect, the dose may need to be lowered by up to 50%. Because this phenomenon is difficult to predict on an individual basis, any opioid conversion requires close monitoring.

Similarly, patients who are being converted from a long-acting opioid formulation should first be stabilized on the immediate-release form of the new drug. Once a stable standing dose is re-established, a slow-release dose can be introduced.


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