When should a patient with severe pain be switched from morphine to Dilaudid (hydromorphone)?

When to Switch from Morphine to Hydromorphone

Switch from morphine to hydromorphone when the patient experiences inadequate analgesia despite dose escalation, intolerable side effects (particularly nausea, vomiting, pruritus, or sedation), or has renal impairment where morphine's active metabolites accumulate. 1, 2

Primary Indications for Opioid Rotation to Hydromorphone

Inadequate Analgesia Despite Morphine Titration

• When pain control remains suboptimal after appropriate morphine dose escalation, rotation to hydromorphone can recapture analgesia in patients who have developed tolerance or incomplete response 2
• Hydromorphone demonstrates a quicker onset of action compared to morphine, making it potentially superior for acute severe pain that is not responding adequately to morphine 1, 3
• In clinical studies, approximately 43% of patients (6 of 16) who were switched to hydromorphone due to poor pain relief with morphine achieved at least 25% improvement in analgesic response 2

Intolerable Side Effects from Morphine

• The most common reason to switch is pharmacological complications, accounting for 57% of conversions in chronic pain patients 2
• Specific side effects that improve with hydromorphone rotation include:
  • Nausea and vomiting 2
  • Pruritus (notably, hydromorphone caused 0% pruritus versus 6% with morphine in one randomized trial) 3
  • Sedation 2
  • Peripheral edema (though this may recur with prolonged hydromorphone exposure) 2

Renal Impairment

• Hydromorphone is safer than morphine in patients with renal failure, though caution is still required 1
• Start with one-fourth to one-half the usual calculated dose in patients with renal impairment, as hydromorphone exposure increases 2-fold in moderate and 3-fold in severe renal impairment 1
• Morphine's active metabolites (morphine-3-glucuronide and morphine-6-glucuronide) accumulate significantly in renal failure, causing increased toxicity risk 1
• While hydromorphone also has active metabolites that can accumulate between dialysis treatments, the safety profile is superior to morphine 1

Conversion Algorithm from Morphine to Hydromorphone

Step 1: Calculate Total Daily Morphine Dose

• Sum all scheduled morphine doses plus average daily breakthrough medication use over the past 24-48 hours 4
• Include both immediate-release and extended-release formulations 4

Step 2: Apply Conversion Ratio

• For IV to IV conversion: Use a 5:1 ratio (10 mg IV morphine = 2 mg IV hydromorphone) 1, 4
• For oral to oral conversion: Use approximately 5:1 to 7.5:1 ratio 1, 4
• The CDC conversion factor for calculating morphine milligram equivalents is 4:1 (1 mg hydromorphone = 4 MME), though clinical conversion ratios differ slightly 4

Step 3: Reduce for Incomplete Cross-Tolerance

• Reduce the calculated equianalgesic dose by 25-50% to account for incomplete cross-tolerance 1, 4
• This safety reduction is critical when switching between any opioids 4

Step 4: Divide into Appropriate Dosing Schedule

• For immediate-release oral hydromorphone: Divide total daily dose into every 4-hour scheduled doses 1
• For extended-release formulations: Divide into every 12-hour or every 24-hour dosing depending on formulation 5, 6
• For IV continuous infusion: Calculate hourly rate from total daily dose 1

Step 5: Prescribe Breakthrough Medication

• Provide immediate-release hydromorphone for breakthrough pain at 10-20% of the total 24-hour dose 1
• For patients on extended-release formulations, breakthrough doses should be one-eighth to one-sixth of the daily dose 5
• Administer breakthrough doses every 15 minutes for IV or every 60 minutes for oral as needed 1

Practical Conversion Examples

Example 1: IV Morphine to IV Hydromorphone

• Patient receiving 10 mg IV morphine every 4 hours (60 mg/day total)
• Apply 5:1 ratio: 60 mg morphine ÷ 5 = 12 mg hydromorphone
• Reduce by 25-50%: 6-9 mg hydromorphone per day
• Divide into doses: 1-1.5 mg IV every 4 hours 1, 4

Example 2: Oral Morphine to Oral Hydromorphone

• Patient receiving 180 mg oral morphine per day
• Apply 5:1 ratio: 180 mg ÷ 5 = 36 mg hydromorphone
• Reduce by 25-50%: 18-27 mg hydromorphone per day
• Divide into doses: 3-4.5 mg every 4 hours for immediate-release 4

Clinical Advantages of Hydromorphone Over Morphine

Pharmacokinetic Benefits

• Faster onset of action, reducing time to pain relief 1, 3
• Higher potency (5-7 times more potent than morphine) allows smaller volume administration, beneficial for patient-controlled analgesia and subcutaneous routes 1, 4
• Shorter onset of action supports more frequent dosing intervals for optimal acute pain control 1

Safety Profile Advantages

• Lower risk of dose stacking due to quicker onset, reducing respiratory depression risk 1
• Less problematic metabolite accumulation compared to morphine, particularly in renal impairment 4
• Significantly lower incidence of pruritus 3

Critical Monitoring After Conversion

Initial 24-48 Hours

• Assess pain intensity and side effects every 60 minutes for oral hydromorphone 1
• Monitor respiratory rate and oxygen saturation closely, as respiratory depression can occur at any time, particularly during initiation 1
• Track number of breakthrough doses required 1

Dose Adjustment Criteria

• If more than 3-4 breakthrough doses are required per day, increase the scheduled baseline dose by 25-50% rather than shortening the dosing interval 1
• Re-evaluate within 24 hours after dose adjustment, as steady state is reached within this timeframe 1
• If pain control remains inadequate after 2-3 cycles of breakthrough dosing, consider alternative management strategies 1

Essential Safety Considerations

Prophylactic Measures

• Institute a stimulant or osmotic laxative in all patients receiving sustained hydromorphone unless contraindicated 1
• For patients with history of nausea, provide prophylactic antiemetics 1
• Have naloxone readily available, diluted in normal saline for administration every 30-60 seconds if needed 1

Special Population Adjustments

• Elderly patients (>70 years): Start at the lower end of dosing ranges 1
• Hepatic impairment: Reduce calculated dose by one-fourth to one-half, as exposure increases 4-fold in moderate hepatic impairment 1
• Renal impairment: Start with one-fourth to one-half the usual dose 1

Common Pitfalls to Avoid

• Do not use the same conversion ratios when converting from methadone to hydromorphone—methadone requires unique, dose-dependent conversion ratios 4
• Do not simply add more PRN doses without adjusting the scheduled regimen, as this leads to inconsistent pain control 1
• Avoid mixed agonist-antagonist opioids (like nalbuphine or butorphanol) in combination with hydromorphone, as this could precipitate withdrawal 1
• Do not prescribe extended-release formulations for opioid-naive patients with acute pain 1
• Monitor for myoclonus, especially with chronic use, renal failure, or dehydration—if it occurs, decrease the dose or rotate to a different opioid 1