What is the equivalent dose of hydromorphone (Hydromorph Contin) BID for a patient taking morphine (Contin) 100mg BID?

Converting Morphine Contin 100mg BID to Hydromorph Contin BID

For a patient taking morphine (Contin) 100mg BID (total 200mg/day oral morphine), convert to hydromorphone (Hydromorph Contin) using a 5:1 ratio, yielding 40mg/day oral hydromorphone, then reduce by 25-50% for incomplete cross-tolerance to arrive at 20-30mg/day hydromorphone, divided as 10-15mg BID. 1, 2

Step-by-Step Conversion Algorithm

Step 1: Calculate Total Daily Morphine Dose

• The patient is taking 100mg BID = 200mg oral morphine per day 3

Step 2: Apply Morphine-to-Hydromorphone Conversion Ratio

• Use a 5:1 conversion ratio (oral morphine to oral hydromorphone), which is the standard recommended by multiple guidelines 1, 4, 5, 6
• The CDC conversion factor confirms hydromorphone is approximately 5 times more potent than morphine 3, 2
• Calculation: 200mg morphine ÷ 5 = 40mg oral hydromorphone per day 1, 2

Step 3: Reduce for Incomplete Cross-Tolerance

• Reduce the calculated dose by 25-50% to account for incomplete cross-tolerance when switching between opioids 1, 2
• This yields: 40mg × 0.5 to 0.75 = 20-30mg hydromorphone per day 1
• This critical step prevents overdosing during opioid rotation 1, 2

Step 4: Divide into BID Dosing

• For BID administration: 20-30mg ÷ 2 = 10-15mg hydromorphone BID 1
• Start at the lower end (10mg BID) if the patient had good pain control on morphine 1
• Start at the higher end (15mg BID) if pain was poorly controlled on morphine 1

Breakthrough Pain Management

• Provide immediate-release hydromorphone for breakthrough pain at 10-20% of the total daily dose 1
• For a patient on 20-30mg/day total, breakthrough doses should be 2-4mg oral hydromorphone 1
• Assess efficacy and side effects every 60 minutes after breakthrough dosing 1

Monitoring and Titration

• Monitor closely after conversion for both pain control and adverse effects 2
• If the patient requires more than 3 breakthrough doses per day, increase the scheduled dose rather than the frequency 1
• Upward titration can be done after 24-48 hours if pain control is inadequate 1, 5

Critical Safety Considerations

• Institute prophylactic bowel regimen with stimulant laxatives, as constipation is universal with opioid therapy 1
• In renal impairment, reduce the calculated dose by an additional 25-50%, as hydromorphone exposure increases 2-3 fold in renal dysfunction 1
• In hepatic impairment, reduce the calculated dose by an additional 25-50%, as exposure increases 4-fold in moderate hepatic impairment 1

Common Pitfalls to Avoid

• Do not use a simple 1:5 ratio without dose reduction—this ignores incomplete cross-tolerance and risks overdosing 1, 2
• Do not use conversion ratios of 1:8, which are too conservative and may lead to inadequate pain control; the 1:5 ratio with 25-50% reduction is the evidence-based approach 7, 5, 6
• Avoid fixed conversion ratios without clinical judgment—consider patient-specific factors such as age, organ function, and prior pain control 1