From the Guidelines
To calculate equianalgesic doses between morphine and hydromorphone, use the conversion ratio of 5:1 (oral) or 5:1 (parenteral) as stated in the study by 1. This means 5 mg of oral morphine is equivalent to 1 mg of oral hydromorphone, and 5 mg of parenteral morphine equals 1 mg of parenteral hydromorphone. For example, if a patient is taking 30 mg of oral morphine every 4 hours, the equivalent dose of oral hydromorphone would be 6 mg every 4 hours (30 mg ÷ 5 = 6 mg). When converting between these opioids, it's essential to consider the patient's current opioid regimen and adjust the dose accordingly, as suggested by 1. The study by 1 provides a case example of converting IV morphine to IV hydromorphone, where the patient's total daily IV morphine dose is calculated, and then the equianalgesic dose of IV hydromorphone is determined using a conversion table. The calculated equianalgesic dose is then reduced by 25-50% to account for incomplete cross-tolerance and individual patient variability, as recommended by 1. It's crucial to closely monitor the patient for pain control and side effects after conversion and adjust the dose as needed. Hydromorphone is more potent than morphine due to its higher lipid solubility and greater ability to cross the blood-brain barrier, which explains the 5:1 conversion ratio, as mentioned in 1. Remember that these are general guidelines, and individual patient factors such as age, renal function, and prior opioid exposure may necessitate further dose adjustments, as noted in 1.
Some key points to consider when calculating equianalgesic doses between morphine and hydromorphone include:
- Using the conversion ratio of 5:1 (oral) or 5:1 (parenteral) as stated in 1
- Calculating the patient's total daily opioid dose and adjusting the dose accordingly, as suggested by 1
- Reducing the calculated equianalgesic dose by 25-50% to account for incomplete cross-tolerance and individual patient variability, as recommended by 1
- Closely monitoring the patient for pain control and side effects after conversion and adjusting the dose as needed, as mentioned in 1 and 1
- Considering individual patient factors such as age, renal function, and prior opioid exposure when adjusting the dose, as noted in 1
From the FDA Drug Label
In another trial, 5 mg and 10 mg of hydromorphone hydrochloride oral solution were compared to 30 mg and 60 mg of morphine sulfate oral liquid. The pain relief provided by 5 mg and 10 mg hydromorphone hydrochloride oral solution was comparable to 30 mg and 60 mg oral morphine sulfate, respectively. The calculated equianalgesic dose between morphine and hydromorphone is as follows:
- 5 mg of hydromorphone is equivalent to 30 mg of morphine
- 10 mg of hydromorphone is equivalent to 60 mg of morphine 2
From the Research
Equianalgesic Dose Calculation
The equianalgesic dose between morphine and hydromorphone can be calculated based on the conversion ratios provided in the studies.
- A study published in 2017 3 found that 1 mg of IV hydromorphone is equivalent to 11.46 mg of morphine equivalent daily dose (MEDD).
- Another study published in 2018 4 confirmed that a morphine to hydromorphone conversion ratio of 1:5 or 1:8 can be effective for pain control.
- A study published in 2006 5 used a conversion ratio of 8:1 mg of oral morphine to oral ER hydromorphone HCl.
- A study published in 1996 6 suggested a morphine to hydromorphone use ratio of 3:1.
Conversion Ratios
The conversion ratios between morphine and hydromorphone vary across studies, including: