Hydromorphone (Dilaudid) to Morphine Conversion Ratio
The conversion ratio from hydromorphone (Dilaudid) to morphine is 1:5, meaning 1 mg of hydromorphone is equivalent to approximately 5 mg of morphine. 1
Conversion Ratios by Route of Administration
Oral Route
- Oral hydromorphone to oral morphine: 1:5 ratio
- Example: 10 mg oral hydromorphone = 50 mg oral morphine
Parenteral Route
- IV/SC hydromorphone to IV/SC morphine: 1:5 ratio
- Example: 2 mg IV hydromorphone = 10 mg IV morphine
Route Conversion Factors
When converting between routes for the same medication:
- Oral to IV hydromorphone: 5:1 ratio (oral dose is 5 times the IV dose) 2
- IV to oral hydromorphone: 1:2.5 ratio (oral dose is 2.5 times the IV dose) 3
Clinical Application
Step-by-Step Conversion Process
- Calculate the total daily dose of current opioid (hydromorphone or morphine)
- Apply the appropriate conversion ratio (1:5 for hydromorphone to morphine)
- Reduce the calculated dose by 25-30% to account for incomplete cross-tolerance
- Divide the total daily dose into appropriate dosing intervals based on formulation
Example Conversions
Converting from 12 mg/day oral hydromorphone to oral morphine:
- 12 mg × 5 = 60 mg morphine equivalent
- After 25% reduction for cross-tolerance: 45 mg/day oral morphine
Converting from 30 mg/day IV hydromorphone to oral morphine:
- First convert to oral hydromorphone: 30 mg × 2.5 = 75 mg oral hydromorphone
- Then convert to oral morphine: 75 mg × 5 = 375 mg oral morphine
- After cross-tolerance reduction: approximately 280 mg/day oral morphine
Important Clinical Considerations
Potency Differences
- Hydromorphone is approximately 5 times more potent than morphine 4
- This higher potency means smaller volumes are needed for equivalent analgesia, making hydromorphone particularly useful for patients requiring high doses
Patient Monitoring
- Close monitoring is essential during the first 24-48 hours after conversion
- Watch for signs of:
- Oversedation
- Respiratory depression
- Inadequate pain control
- Withdrawal symptoms
Special Populations
- For elderly patients or those with renal impairment, consider using a more conservative conversion ratio and start with lower doses
- In patients with severe renal impairment, hydromorphone may be preferred over morphine due to fewer active metabolites 5
Common Pitfalls
- Using incorrect conversion ratios (particularly confusing hydromorphone with other opioids)
- Failing to account for incomplete cross-tolerance when switching between opioids
- Not considering the patient's previous opioid exposure and tolerance level
- Overlooking differences in duration of action between formulations
The 1:5 ratio for hydromorphone to morphine conversion is well-established and consistent across multiple guidelines, though individual patient response may vary based on factors such as age, renal/hepatic function, and prior opioid exposure 1, 4.