How to convert oral hydromorphone to parenteral (intravenous) administration?

Converting Oral Hydromorphone to Intravenous Administration

When converting from oral hydromorphone to intravenous administration, use a ratio of 5:1 (oral:IV), which means dividing the oral dose by 5 to determine the equivalent IV dose. 1

Conversion Process

• The average relative potency ratio of oral to intravenous hydromorphone is approximately 2.5:1, meaning 2.5 mg of oral hydromorphone is equivalent to 1 mg of IV hydromorphone 1
• When converting from oral to IV hydromorphone, divide the total daily oral dose by 2.5 to calculate the equianalgesic IV dose 1
• After calculating the equianalgesic IV dose, consider reducing the calculated dose by 25-30% to account for individual variability and incomplete cross-tolerance 2
• Divide the total daily IV dose by 24 to determine the hourly infusion rate for continuous IV administration 2

Administration Guidelines

• For IV administration, administer the dose slowly, over at least 2-3 minutes, to minimize the risk of adverse effects such as hypotension and respiratory depression 3
• Rapid IV injection increases the possibility of side effects and should be avoided 3
• For patients requiring continuous parenteral opioids, IV infusion may be preferred in patients who already have an in-dwelling IV line, those with generalized edema, coagulation disorders, or poor peripheral circulation 4
• If IV access is problematic, subcutaneous infusion can be used at the same dose as IV infusion, as the relative potency between IV and subcutaneous routes is approximately 1:1 2

Breakthrough Pain Management

• Provide rescue doses for breakthrough pain at 10-15% of the total daily IV dose 2
• Breakthrough doses can be administered every 1-2 hours as needed 2
• Titrate the dose upward as needed based on pain control and side effects 2

Special Considerations

• Use hydromorphone with caution in patients with renal impairment as metabolites may accumulate 4, 2
• Consider dose reduction (start with one-fourth to one-half the usual dose) in patients with significant renal or hepatic dysfunction 3
• Higher doses may require more careful monitoring for adverse effects such as respiratory depression 2, 3
• Assess pain intensity regularly using validated pain scales to guide dose adjustments 4

Example Conversion

For a patient taking 16 mg of oral hydromorphone daily:

1. Calculate the equianalgesic IV dose: 16 mg ÷ 2.5 = 6.4 mg IV hydromorphone per day
2. Consider dose reduction for safety: 6.4 mg × 0.75 = 4.8 mg IV hydromorphone per day
3. Calculate hourly infusion rate: 4.8 mg ÷ 24 = 0.2 mg/hour
4. Determine breakthrough dose: 4.8 mg × 0.15 = 0.72 mg (rounded to 0.7 mg) every 1-2 hours as needed

Monitoring and Titration

• Individually titrate to a dose that provides adequate analgesia while minimizing adverse reactions 3
• Continually reassess patients for maintenance of pain control and development of adverse effects 3
• If pain increases after dosage stabilization, identify the source of increased pain before increasing the dose 3
• If unacceptable opioid-related adverse reactions occur, consider reducing the dosage 3