What is the intravenous (IV) hydromorphone equivalent to 30 milligrams (mg) of intravenous (IV) morphine?

IV Hydromorphone Equivalence to IV Morphine

The intravenous (IV) hydromorphone equivalent to 30 mg of IV morphine is approximately 6 mg, based on a conversion ratio of 5:1 (morphine:hydromorphone). 1

Conversion Ratios and Evidence

The conversion between IV morphine and IV hydromorphone is important for effective pain management while minimizing adverse effects. The evidence supports the following conversion factors:

• The most recent and highest quality evidence indicates a morphine to hydromorphone ratio of 5:1 for IV to IV conversion 1
• This means that 1 mg of IV hydromorphone is approximately equivalent to 5 mg of IV morphine
• Therefore, 30 mg of IV morphine ÷ 5 = 6 mg of IV hydromorphone

It's worth noting that some older studies suggested different conversion ratios:

• A 1996 study found a clinical analgesic equivalence ratio of 3:1 (morphine:hydromorphone) in patients using prolonged PCA for severe pain 2
• Traditional conversion ratios have sometimes used 7:1, though this appears to be less accurate in clinical practice

Clinical Application and Safety Considerations

When converting between opioids, several important clinical considerations should be kept in mind:

• Dose reduction for safety: When converting between opioids, consider reducing the calculated dose by 25-50% due to incomplete cross-tolerance to minimize risk of respiratory depression 3
• Patient monitoring: After conversion, monitor vital signs closely (every 15 minutes for the first hour, then hourly for 4 hours, then every 4 hours) 3
• Pain assessment: Evaluate pain scores every 30-60 minutes until stable, then every 4 hours 3
• Respiratory safety: Ensure respiratory rate remains ≥8/min to continue opioid administration 3

Special Patient Populations

Dose adjustments may be necessary for certain patient populations:

• Elderly patients: Consider using the lower end of the dosing range (25-50% reduction) 3
• Renal/hepatic impairment: Reduce calculated doses by 25-50% due to potential accumulation of metabolites 3
• High-dose conversions: Patients receiving ≥30 mg of IV hydromorphone/day may require a lower conversion ratio (approximately 9.86:1 rather than 11.46:1 when converting to oral morphine equivalents) 1

Common Pitfalls to Avoid

• Confusing different routes: IV to IV conversion ratios differ from IV to oral conversion ratios. For example, the IV to oral hydromorphone conversion ratio is approximately 1:2.5 1
• Failure to account for cross-tolerance: Not reducing the calculated dose when switching between opioids can lead to overdose
• Inadequate monitoring: Respiratory depression is a serious risk with IV opioids, requiring close monitoring of vital signs 3
• Neuroexcitatory side effects: At high doses, morphine and hydromorphone metabolites can cause neuroexcitatory effects (allodynia, myoclonus, seizures) 4