What is the equivalent oral (PO) dose of hydromorphone 0.125mg given subcutaneously (SC)?

Hydromorphone Subcutaneous to Oral Conversion

Hydromorphone 0.125mg SC is equivalent to approximately 0.625mg PO based on a 5:1 oral-to-parenteral conversion ratio. 1

Conversion Calculation

The conversion from subcutaneous to oral hydromorphone follows these principles:

• Hydromorphone has a 5:1 oral-to-parenteral conversion ratio according to the National Comprehensive Cancer Network (NCCN) guidelines 1
• Subcutaneous and intravenous routes are considered equipotent for hydromorphone 1

Therefore:

• 0.125mg SC hydromorphone × 5 = 0.625mg PO hydromorphone

Evidence Supporting This Conversion

The 5:1 conversion ratio is well-established in clinical practice guidelines:

• The NCCN guidelines specifically recommend using a 5:1 oral-to-parenteral conversion ratio for hydromorphone 2
• More recent evidence from Praxis Medical Insights confirms this 5:1 conversion ratio when converting between oral and parenteral hydromorphone 1

Clinical Considerations

When implementing this conversion in practice:

• Consider reducing the calculated equianalgesic dose by 25-50% if switching between different opioids to account for incomplete cross-tolerance 2
• For this specific conversion (same medication, different route), the 5:1 ratio can be applied directly
• Monitor for efficacy and side effects after conversion, as individual patient response may vary

Special Populations and Cautions

• Renal impairment: Use caution when administering hydromorphone to patients with kidney dysfunction, as metabolites can accumulate and potentially cause neurotoxicity even at low doses 3
• Elderly patients: May be more sensitive to both therapeutic and adverse effects of hydromorphone
• Opioid-naïve patients: Consider starting with lower doses and titrating carefully

Practical Application

For a patient receiving 0.125mg SC hydromorphone:

1. Calculate oral equivalent: 0.125mg × 5 = 0.625mg PO
2. Round to nearest available dosage form if needed (typically 2mg, 4mg, or 8mg tablets)
3. Consider splitting tablets or using liquid formulation for more precise dosing
4. Monitor for adequate pain control and adjust as needed

Remember that hydromorphone is a potent opioid (approximately 5-7 times more potent than oral morphine) 1, so precise dosing is essential for both efficacy and safety.