From the Guidelines
The conversion ratio between IV morphine and IV hydromorphone (Dilaudid) is approximately 5:1, meaning 5 mg of IV morphine is equivalent to 1 mg of IV hydromorphone, as indicated by the morphine milligram equivalent doses for commonly prescribed opioids for pain management 1. When converting between these medications, it is essential to start with a conservative dose and titrate as needed based on patient response.
- Hydromorphone is more potent and lipophilic than morphine, which explains its higher potency ratio.
- It typically has a faster onset (2-5 minutes) and shorter duration of action (2-3 hours) compared to morphine (onset 5-10 minutes, duration 3-4 hours) 1.
- Hydromorphone may be preferred in patients with renal impairment as it produces fewer active metabolites than morphine.
- Both medications can cause similar side effects including respiratory depression, sedation, nausea, constipation, and pruritus, so monitor patients closely after conversion. The conversion factor for hydromorphone is 5.0, as shown in the table of morphine milligram equivalent doses for commonly prescribed opioids for pain management 1.
- To convert IV morphine to IV hydromorphone, determine the total amount of current IV morphine in a 24-h period for the patient.
- Calculate the equianalgesic dose of IV hydromorphone using the conversion factor.
- Reduce the dose of hydromorphone by 25%-50% if the patient was effectively controlled with IV morphine, as suggested in the case example of converting IV morphine to IV hydromorphone 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
IV Morphine and IV Dilaudid Conversion
- The conversion ratio between IV morphine and IV hydromorphone (Dilaudid) has been studied in various clinical settings 2, 3, 4, 5, 6.
- A study published in 1996 found a morphine to hydromorphone equivalence ratio of 3:1 in patients with severe oral mucositis 2.
- Another study published in 2021 found that the equipotency ratio of hydromorphone to morphine is closer to 1:6.5 rather than the commonly employed 1:5 ratio 5.
- A meta-analysis published in 2011 suggested that hydromorphone provides slightly better clinical analgesia than morphine, with a small effect-size (Cohen's d=0.266) 6.
- A study published in 2023 found that IV morphine and hydromorphone have different onset, magnitude, duration, and variability of analgesic and ventilatory effects 4.
- The interindividual variability in clinical effects did not differ between opioids in some studies 3, 4.
Key Findings
- The conversion ratio between IV morphine and IV hydromorphone may vary depending on the clinical setting and population being studied.
- Hydromorphone may have a better clinical profile than morphine in some cases, with slightly better analgesia and similar side-effects 4, 6.
- The equipotency ratio of hydromorphone to morphine is still a topic of debate, with different studies suggesting different ratios 2, 5.