Opioid Conversion Calculator
Convert between different opioid medications with equianalgesic dosing and cross-tolerance adjustment
Convert Between Opioid Medications
Oral morphine with lower bioavailability
Total daily dose of current medication
Oral oxycodone - commonly prescribed
Recommended 25-50% dose reduction due to incomplete cross-tolerance between opioids
Example Conversion
Converting from Oral Morphine to Oxycodone
Patient situation: 60mg/day oral morphine, inadequate pain control
Plan: Convert to oral oxycodone
Morphine oral factor: 1/3 (relative to IV morphine)
Oxycodone oral factor: 2/3 (relative to IV morphine)
Calculation Steps
1. Morphine IV equivalent: 60 × (1/3) = 20mg IV morphine
2. Raw oxycodone dose: 20 ÷ (2/3) = 30mg oxycodone
3. Cross-tolerance adjustment (25%): 30 × 0.75 = 22.5mg
Recommended dose: 22.5mg oxycodone daily
Equianalgesic Doses
Safety Guidelines
Always apply 25-50% dose reduction for incomplete cross-tolerance
Start with lower doses and titrate up based on response
Consider patient-specific factors (age, renal function, tolerance)
Monitor closely for respiratory depression and side effects
Verify calculations with clinical guidelines and colleagues
Understanding Opioid Conversion
What is Opioid Conversion?
Opioid conversion (rotation) is the clinical practice of switching a patient from one opioid medication to another or changing the route of administration. This is done when current therapy is ineffective, causes intolerable side effects, or when clinical circumstances require a change.
Why Convert Opioids?
- •Inadequate pain control with current medication
- •Intolerable side effects or adverse reactions
- •Change in route of administration needed
- •Drug availability or cost considerations
Cross-tolerance
Cross-tolerance refers to the phenomenon where tolerance to one opioid confers partial tolerance to other opioids. However, this tolerance is often incomplete, meaning patients may be more sensitive to the new opioid than expected.
Recommended Dose Reductions:
- • Standard conversions: 25-50% reduction
- • High-dose patients: Up to 50% reduction
- • Elderly patients: Consider larger reductions
- • Renal/hepatic impairment: Additional considerations
Important: These calculations provide starting doses only. Clinical judgment, patient monitoring, and individualized titration are essential for safe and effective therapy.