From the Guidelines
The equivalent dose of oxycodone (OxyContin) for a patient taking 60mg of morphine sulfate daily is approximately 40mg of oxycodone daily, based on the most recent and highest quality study available 1. When converting between opioids, it's essential to use equianalgesic conversion ratios. According to the study, oral oxycodone is about 1.5-2 times more potent than oral morphine 1. Therefore, 60mg of morphine divided by 1.5 equals 40mg of oxycodone. Some key points to consider when making this conversion include:
- Starting with a slightly lower dose (perhaps 30-35mg of oxycodone daily) and titrating up as needed to control pain while monitoring for side effects 1.
- Accounting for incomplete cross-tolerance between different opioids and individual patient variability in response.
- Monitoring the patient closely during the first few days after conversion for adequate pain control and potential side effects such as sedation, constipation, or respiratory depression.
- Ensuring the conversion is done under medical supervision, and the total daily dose is divided appropriately based on the specific oxycodone formulation being used. It's also worth noting that the relative effectiveness of opioids can vary considerably between individual patients, and switching to another opioid should be done cautiously with a dose reduction of the newly prescribed opioid 1.
From the Research
Equivalent Dose of Oxycodone
To determine the equivalent dose of oxycodone for a patient taking 60mg of morphine daily, we need to consider the conversion ratio between morphine and oxycodone.
- The study by 2 suggests a ratio of 1:2 for oral morphine to oxycodone, implying that 1mg of morphine is equivalent to 2mg of oxycodone.
- Another study by 3 supports a 1:1 milligram conversion ratio for oral morphine and oral oxycodone.
- However, the study by 4 observed analgesic synergy in morphine and oxycodone combinations, with a fixed ratio of 3:2 or 1:2, but does not provide a direct conversion ratio.
Calculation of Equivalent Dose
Based on the 1:2 ratio from 2, the equivalent dose of oxycodone for a patient taking 60mg of morphine daily would be:
- 60mg of morphine / 2 = 30mg of oxycodone Using the 1:1 ratio from 3, the equivalent dose would be:
- 60mg of morphine = 60mg of oxycodone
Considerations
It is essential to note that individual patient responses to opioids can vary, and these conversion ratios are only a guide.