Opioid Substitution for Hydrocodone 30 mg Daily
Prescribe as-needed immediate-release oxycodone, 20 mg total in divided doses daily (Answer C).
Conversion Rationale
The appropriate substitution requires understanding equianalgesic dosing between hydrocodone and oxycodone:
Hydrocodone may be approximately equipotent with oral morphine, though its equivalence data are not substantiated 1. Clinical experience suggests variable effective dosing 1.
Using standard equianalgesic conversion principles: If we consider hydrocodone roughly equivalent to morphine on a 1:1 basis (30 mg hydrocodone ≈ 30 mg oral morphine), and oxycodone is approximately 1.5 times more potent than morphine, the conversion would be: 30 mg hydrocodone ÷ 1.5 = 20 mg oxycodone daily 1.
This patient is already opioid-tolerant (taking 30 mg hydrocodone daily chronically), so they require continuation of adequate analgesia, not initiation at opioid-naïve doses 1.
Why Other Options Are Incorrect
Option A (10 mg oxycodone daily) significantly under-doses this patient, providing only one-third of their current opioid requirement, which would result in inadequate pain control and potential withdrawal symptoms 1.
Options B and D (ibuprofen or acetaminophen alone) are completely inappropriate for a patient already requiring chronic opioid therapy. Non-opioid analgesics cannot substitute for established opioid requirements in opioid-tolerant patients 1.
Option E (40 mg oxycodone daily) over-estimates the conversion and could lead to oversedation or respiratory depression. When converting between opioids, a dose reduction of 25-50% is often recommended to account for incomplete cross-tolerance 1, making 20 mg more appropriate than 40 mg.
Clinical Context Considerations
This patient has metastatic melanoma with fever and infection, requiring hospitalization. Maintaining adequate pain control during acute illness is essential for quality of life 1.
The patient is alert, oriented, and hemodynamically stable (no acute distress, normal vital signs except fever), indicating they can safely continue oral opioid therapy 1.
Immediate-release formulations are appropriate for this as-needed dosing regimen, consistent with guideline recommendations for short-acting opioids 1.
Implementation Strategy
Prescribe oxycodone 5 mg tablets, to be taken as needed every 4-6 hours (maximum 20 mg daily in divided doses), maintaining the same PRN dosing pattern as the previous hydrocodone regimen 1.
Monitor closely during the first 24-48 hours for signs of inadequate analgesia or excessive sedation, as individual responses to opioid conversion vary 1.
Reassess pain control and adjust dosing if the patient requires consistently higher or lower doses than the initial conversion suggests 1.