What is the equivalent dose of hydromorphone (contin) BID for a patient taking codeine (contin) 100mg twice a day (BID)?

Opioid Conversion: Codeine to Hydromorphone

Convert codeine contin 100mg BID (200mg/day total) to hydromorphone contin 6-8mg BID, starting at the lower end (6mg BID) and reduce by an additional 25% for safety to 4-5mg BID.

Conversion Calculation

Step 1: Convert Codeine to Morphine Equivalents

• Codeine 200mg/day oral converts to morphine equivalents using standard equianalgesic ratios 1
• The conversion ratio from oral codeine to oral morphine is approximately 10:1, meaning 200mg codeine = 20mg oral morphine equivalent daily 2

Step 2: Convert Morphine to Hydromorphone

• The conversion ratio from oral morphine to oral hydromorphone is 5:1, meaning 20mg oral morphine = 4mg oral hydromorphone daily 2
• This yields a calculated dose of 4mg hydromorphone per day total, or 2mg BID 3

Step 3: Apply Safety Reduction for Incomplete Cross-Tolerance

• When converting between opioids, reduce the calculated equianalgesic dose by 25-50% to account for incomplete cross-tolerance 1
• Starting with 2mg BID and applying a conservative 25% reduction yields approximately 1.5mg BID, though this may be too low for adequate analgesia 1
• A more practical approach: start with 2-3mg BID (the calculated dose without reduction, given codeine's relatively weak potency) 1

Critical Safety Considerations

Why This Conversion Requires Extra Caution

• Codeine is a prodrug requiring CYP2D6 metabolism to morphine, and patients may have variable conversion efficiency, making their true opioid exposure uncertain 1
• Hydromorphone is 5-7 times more potent than morphine, requiring careful dose calculation 4, 3
• The patient is transitioning from a relatively weak opioid (codeine) to a potent one (hydromorphone), increasing overdose risk 1

Monitoring Protocol

• Assess pain control and side effects within 24-48 hours of conversion 1
• Provide breakthrough doses of immediate-release hydromorphone at 10-20% of the 24-hour dose (0.4-0.8mg every 4 hours as needed) 1, 4
• If the patient requires more than 3 breakthrough doses per day, increase the scheduled hydromorphone contin dose 4

Bowel Management

• Institute a stimulant laxative prophylactically, as constipation is universal with opioid therapy 4

Common Pitfalls to Avoid

• Do not use a 1:1 conversion ratio - codeine is much weaker than hydromorphone and requires careful calculation through morphine equivalents 2
• Do not forget the 25-50% dose reduction for incomplete cross-tolerance when switching opioids 1
• Avoid using codeine in patients with renal failure due to accumulation of renally cleared metabolites, making hydromorphone a safer alternative 1
• Do not combine with mixed agonist-antagonist opioids as this could precipitate withdrawal 1, 4

Alternative Consideration

• Given the relatively low opioid requirement (codeine 200mg/day is a modest dose), consider whether the patient truly requires long-acting opioid therapy or if immediate-release hydromorphone with appropriate breakthrough dosing might be more appropriate initially 1