What is the equivalent oral (PO) dose of hydromorphone for a patient receiving 0.8 mg of intravenous (IV) hydromorphone?

IV to Oral Hydromorphone Conversion

For 0.8 mg IV hydromorphone, the equivalent oral dose is 2 mg PO hydromorphone.

Conversion Ratio

The conversion from IV to oral hydromorphone follows a well-established ratio:

• The standard conversion ratio is 1:2.5, meaning 1 mg IV hydromorphone equals approximately 2.5 mg oral hydromorphone 1
• This ratio is supported by clinical research in cancer patients showing a median conversion ratio of 2.5 (interquartile range 2.14-2.75) with strong correlation (0.95, P < 0.0001) 1
• For your specific dose: 0.8 mg IV × 2.5 = 2 mg PO hydromorphone

Dosing Considerations

Initial oral dosing guidelines:

• The FDA label recommends initiating oral hydromorphone at 2-4 mg every 4-6 hours for opioid-tolerant patients 2
• Your calculated 2 mg dose falls appropriately within this recommended starting range 2

Important pharmacokinetic factors:

• Oral hydromorphone has approximately 24% bioavailability due to extensive first-pass metabolism 2
• Peak plasma concentrations occur within 0.5-1 hour after oral administration 2
• The terminal elimination half-life is approximately 2.6 hours for oral formulations 2

Monitoring and Titration

After conversion, assess the patient:

• Monitor efficacy and adverse effects every 60 minutes for oral hydromorphone 3
• If pain remains inadequately controlled after 2-3 cycles, consider dose adjustment or alternative strategies 3
• Provide breakthrough doses of 10-20% of the total 24-hour dose (approximately 0.4-0.8 mg for a 4 mg/day regimen) 4, 3

Special Population Adjustments

Reduce the calculated dose if:

• Renal impairment: Start with one-fourth to one-half the usual dose, as exposure increases 2-fold in moderate and 3-fold in severe renal impairment 2
• Hepatic impairment: Start with one-fourth to one-half the usual dose, as exposure increases 4-fold in moderate hepatic impairment 2
• Incomplete cross-tolerance: When rotating from other opioids, reduce the calculated dose by 25-50% to account for incomplete cross-tolerance 4, 3

Critical Safety Points

• The conversion ratio may vary at higher doses; patients receiving ≥30 mg/day IV hydromorphone may require a lower conversion ratio 1
• Always round down rather than up when uncertain, as it is safer to underestimate than overestimate the dose 2
• Institute prophylactic bowel regimen with stimulant laxatives, as constipation is universal with opioid therapy 5, 3