From the Guidelines
The patient's daily oxycodone intake of 8-10 tablets, assuming standard 10 mg tablets, translates to 120-150 morphine milligram equivalents (MME) per day, based on the conversion factor of 1.5 from the most recent and highest quality study 1. To calculate this, we first determine the total daily dose of oxycodone, which is 80-100 mg. Then, using the conversion factor provided in the 2022 CDC clinical practice guideline for prescribing opioids for pain - United States, 2022 1, we multiply the oxycodone dose by 1.5 to find the equivalent dose in morphine. This calculation is crucial for assessing the patient's opioid burden and risk stratification, as higher MME values are associated with increased risks of respiratory depression and other opioid-related adverse events. Key points to consider in this calculation include:
- The conversion factor for oxycodone to morphine is 1.5, as indicated in the most recent guideline 1.
- The patient's daily oxycodone dose ranges from 80 mg to 100 mg, based on the intake of 8-10 tablets per day.
- The equivalent morphine dose, and thus the MME, ranges from 120 mg to 150 mg per day.
- It is essential to note that equianalgesic dose conversions are estimates and do not account for individual variability in genetics and pharmacokinetics, as cautioned in the guideline 1.
- Clinicians should use these calculations to evaluate total opioid exposure, especially when patients are on multiple opioids or transitioning between different opioid medications, always keeping in mind the potential for increased risk of overdose and side effects with higher MME values.
From the Research
Calculating Morphine Equivalents
To calculate the morphine equivalents of the patient's daily oxycodone intake, we need to understand the conversion ratio between oxycodone and morphine.
- According to the study 2, the equivalence with regard to morphine is 1:2 for oxycodone, meaning 1 mg of oxycodone is equivalent to 2 mg of morphine in terms of analgesic effect.
- Another study 3 suggests a relative potency ratio of 1:3 for oxycodone to morphine, indicating that 1 mg of oxycodone is equivalent to 3 mg of morphine.
Patient's Daily Oxycodone Intake
The patient takes 2 oxycodone tablets every 4 hours while awake and generally takes 8-10 tablets daily.
- Assuming each tablet is 10 mg (as mentioned in study 4 for a specific formulation), the patient's daily intake would be 80-100 mg of oxycodone.
Conversion to Morphine Equivalents
Using the conversion ratios:
- With a 1:2 ratio 2, 80-100 mg of oxycodone would be equivalent to 160-200 mg of morphine.
- With a 1:3 ratio 3, 80-100 mg of oxycodone would be equivalent to 240-300 mg of morphine.
Considerations
- The actual conversion ratio may vary based on individual patient factors and the specific formulation of oxycodone being used.
- These calculations are based on the available studies and may not reflect the most current or precise conversion ratios.