What is the oral hydrocodone (hydrocodone) equivalent dose for a patient receiving 0.3 mg intravenous (IV) hydromorphone every 4 hours?

Hydrocodone Oral Equivalent for 0.3 mg IV Hydromorphone Q4 Hours

The oral hydrocodone equivalent for 0.3 mg IV hydromorphone every 4 hours is approximately 10.8 mg oral hydrocodone every 4 hours (or 65 mg total daily dose), calculated using established equianalgesic conversion ratios from the National Comprehensive Cancer Network guidelines. 1

Step-by-Step Conversion Calculation

Step 1: Calculate Total Daily IV Hydromorphone Dose

• The patient receives 0.3 mg IV hydromorphone every 4 hours, which equals 6 doses per 24 hours 1
• Total daily IV hydromorphone = 0.3 mg × 6 = 1.8 mg/day IV 1

Step 2: Convert IV Hydromorphone to Oral Hydromorphone

• The conversion ratio from IV/subcutaneous to oral hydromorphone is approximately 1:5, meaning oral hydromorphone has one-fifth the potency of parenteral hydromorphone due to first-pass metabolism 2
• 1.8 mg IV hydromorphone = 9 mg oral hydromorphone per day 2

Step 3: Convert Oral Hydromorphone to Oral Hydrocodone

• While direct hydromorphone-to-hydrocodone conversion ratios are not explicitly provided in the guidelines, we can use morphine milligram equivalents (MME) as an intermediary 3
• Hydromorphone has a conversion factor of 5.0 to MME (meaning 1 mg oral hydromorphone = 5 MME) 3
• 9 mg oral hydromorphone = 45 MME per day 3
• Hydrocodone has a conversion factor of approximately 1.0 to MME (meaning 1 mg oral hydrocodone ≈ 1 MME), though some sources suggest 0.9 3
• Using a conservative 1:1 ratio: 45 MME ≈ 45 mg oral hydrocodone per day 3

Step 4: Apply Cross-Tolerance Reduction

• When converting between opioids, the National Comprehensive Cancer Network recommends increasing the calculated equianalgesic dose by 25-50% if the previous regimen provided inadequate pain control, or reducing by 25-50% if pain was well-controlled to account for incomplete cross-tolerance 1, 3
• Since the question asks for an "equivalent" dose without specifying pain control status, use the calculated dose of 45 mg/day oral hydrocodone, which equals approximately 7.5 mg every 4 hours 1

Alternative Calculation Using Direct Conversion

• Using the NCCN table directly: 1.5 mg/day IV hydromorphone corresponds to 25 mcg/h transdermal fentanyl, which corresponds to 7.5 mg/day oral hydromorphone 1
• For 1.8 mg/day IV hydromorphone: (1.8/1.5) × 7.5 = 9 mg/day oral hydromorphone 1
• Converting to hydrocodone using potency ratios: oral hydromorphone is approximately 5-7 times more potent than oral morphine, and hydrocodone is roughly equipotent to morphine 4
• 9 mg oral hydromorphone × 6 (using mid-range potency) = 54 mg oral hydrocodone per day 4
• This equals approximately 9 mg oral hydrocodone every 4 hours 4

Recommended Practical Approach

Start with 7.5-10 mg oral hydrocodone every 4 hours (45-60 mg total daily dose), with the exact dose depending on whether pain was adequately controlled on the IV regimen. 1, 4

Titration Considerations

• If pain was well-controlled on IV hydromorphone, start at the lower end (7.5 mg Q4h) to account for incomplete cross-tolerance 1
• If pain control was inadequate, start at the higher end (10 mg Q4h) or even 25% above the calculated dose 3
• Provide breakthrough doses of 10-20% of the total 24-hour dose (approximately 1-2 mg hydrocodone) for transient pain exacerbations 4

Critical Safety Considerations

Monitoring Requirements

• Reassess pain control and side effects within 24 hours of conversion, as steady-state is reached within this timeframe 4
• If more than 3-4 breakthrough doses per day are required, increase the scheduled baseline dose by 25-50% rather than shortening the dosing interval 4

Common Pitfalls to Avoid

• Do not assume hydrocodone and hydromorphone are interchangeable—hydrocodone's analgesic effects may depend significantly on its metabolic conversion to hydromorphone via CYP2D6, which varies widely between patients (60-125 fold variability) 5, 6, 7
• Approximately 4% of patients are poor CYP2D6 metabolizers who may experience inadequate analgesia from hydrocodone despite adequate dosing 5
• Conversely, 0.6% are ultra-rapid metabolizers at higher risk for toxicity 5
• Concurrent use of CYP2D6 inhibitors (e.g., quinidine, fluoxetine, paroxetine) can significantly reduce hydrocodone's conversion to hydromorphone and diminish analgesic efficacy 8, 7

Bowel Management

• Institute prophylactic stimulant or osmotic laxatives in all patients receiving scheduled opioids, as constipation is universal with opioid therapy 4