Oral Hydromorphone Equivalent to 1mg IV
The oral equivalent of 1mg IV hydromorphone is approximately 2.5mg oral hydromorphone. 1
Conversion Ratio Evidence
The most robust evidence comes from a 2017 retrospective study of 394 cancer patients that specifically examined conversions from IV to oral hydromorphone in real-world clinical practice. 1 This study found:
- The median conversion ratio from IV to oral hydromorphone was 2.5:1 (interquartile range 2.14-2.75) with excellent correlation (0.95, P < 0.0001) 1
- This means 1mg IV hydromorphone = 2.5mg oral hydromorphone
- The study included 147 patients successfully converted from IV to oral hydromorphone without readmission within one week, providing strong clinical validation 1
Supporting Guideline Evidence
The ESMO clinical guidelines support this conversion by indicating that oral hydromorphone has a relative effectiveness of 7.5 compared to oral morphine, while parenteral forms are not directly listed but the relationship between routes is implied through their comparative tables. 2
Additional guideline evidence confirms that oral hydromorphone is approximately 5 times more potent than oral morphine on a milligram basis, which aligns with the conversion ratios when accounting for route differences. 3
Alternative Conversion Approaches
If converting through morphine equivalents as an intermediate step:
- 1mg IV hydromorphone = approximately 5-7mg IV morphine 3, 4
- IV morphine to oral morphine uses a 1:3 ratio 5
- This yields approximately 15-21mg oral morphine equivalent
- Oral morphine to oral hydromorphone uses a 7.5:1 ratio 2
- This calculates to approximately 2-2.8mg oral hydromorphone
This indirect calculation supports the direct conversion ratio of 2.5:1 from the clinical study. 1
Critical Safety Consideration
When performing any opioid conversion, reduce the calculated dose by 25-50% to account for incomplete cross-tolerance. 3, 5 However, the 2.5:1 ratio from the clinical study already reflects real-world dosing that achieved adequate pain control without overdosing, so this reduction may not be necessary when using this specific conversion ratio. 1
Practical Application
For 1mg IV hydromorphone:
- Start with 2.5mg oral hydromorphone 1
- Provide breakthrough doses of 10-20% of the total 24-hour dose 3
- Reassess within 24 hours as steady state is reached 3
- If more than 3-4 breakthrough doses are needed daily, increase the scheduled baseline dose by 25-50% 3
Common Pitfall to Avoid
Do not use the older 5:1 conversion ratio that is sometimes cited in older literature or general opioid conversion tables. 4 The 2017 clinical study provides more accurate, evidence-based conversion data specifically for IV to oral hydromorphone that reflects actual clinical practice and patient outcomes. 1