Opioid Substitution for Hydrocodone in Cancer Patients
Prescribe as-needed immediate-release oxycodone, 20 mg total in divided doses daily (Option C).
Equianalgesic Conversion Rationale
The patient was taking hydrocodone 30 mg daily, which requires appropriate opioid conversion when substituting with oxycodone:
- Hydrocodone is approximately equipotent with oral morphine (conversion factor of 1), while oxycodone has a conversion factor of 1.5 relative to morphine, making it more potent than hydrocodone 1
- Using standard conversion tables, 30 mg of hydrocodone is equivalent to approximately 20 mg of oxycodone 1
- This provides the most appropriate equianalgesic dose to maintain adequate pain control 1
Why Other Options Are Inadequate
Option A (10 mg oxycodone total daily):
- This represents only about half of the analgesic effect compared to the patient's current 30 mg hydrocodone regimen 1
- Underdosing cancer pain in metastatic disease negatively impacts treatment adherence, quality of life, and overall outcomes 1
Options B and D (Ibuprofen or Acetaminophen alone):
- NSAIDs and acetaminophen alone are typically insufficient for managing moderate to severe cancer pain that previously required strong opioids 1
- Cancer pain, particularly in metastatic melanoma, often requires opioid therapy to maintain quality of life 1
Option E (40 mg oxycodone total daily):
- This exceeds the equianalgesic dose and risks oversedation
- While individual variability exists, starting with the calculated equianalgesic dose and monitoring closely for effect is the appropriate approach 1
Implementation Strategy
- Divide the 20 mg total daily dose appropriately (e.g., 5 mg every 4-6 hours as needed) 1
- Provide breakthrough pain dosing of approximately 10-15% of the total daily dose 1
- Monitor closely for efficacy and adjust based on patient response 1
Critical Considerations in This Patient
Infection Risk Context:
- This patient has fever, elevated leukocyte count (17,000), and is on chemotherapy for metastatic melanoma
- While broad-spectrum antibiotics have been initiated, adequate pain control remains essential for patient comfort and recovery
- Individual patient variability in opioid metabolism may affect response to the new medication, requiring close monitoring 1
- Consider the patient's renal and hepatic function when selecting alternative opioids, as metabolite accumulation can vary between medications 1
Common Pitfall to Avoid
The most critical error would be underdosing (Option A) in a cancer patient with established opioid requirements, as inadequate pain control significantly compromises quality of life and treatment adherence in metastatic disease 1.