Oxycodone Prescription Duration Calculation
If 15 tablets of 5 mg oxycodone are prescribed to be taken every 8 hours, this supply will last 1.875 days (approximately 45 hours), which is inadequate for any meaningful pain management regimen.
Mathematical Calculation
- Dosing frequency: Every 8 hours = 3 doses per day 1
- Total tablets prescribed: 15 tablets
- Duration: 15 tablets ÷ 3 doses per day = 5 days of medication 1
Critical Clinical Context
This prescription represents a total daily dose of 15 mg oxycodone (3 tablets × 5 mg), which converts to 22.5 morphine milligram equivalents (MME) per day using the 1.5:1 conversion factor 2. This dose remains well below the 50 MME/day threshold that triggers increased vigilance for overdose risk 3.
Appropriate Prescribing Considerations
For opioid-naïve patients with acute pain, the FDA-approved initial dosing range is 5-15 mg every 4-6 hours as needed, not every 8 hours 1. The every-8-hour dosing interval prescribed here is:
- Suboptimal for immediate-release oxycodone, which has a duration of action of 3-4 hours and is typically dosed every 4-6 hours 4, 5
- More appropriate for controlled-release formulations, though standard controlled-release oxycodone is dosed every 12 hours 4, 6
Evidence-Based Duration Recommendations
For acute pain conditions treated in emergency settings, research demonstrates that patients consume a median of only 7 tablets of morphine 5 mg equivalent over 14 days 7. To adequately supply 95% of acute pain patients for the first 3 days, only 15 tablets of morphine 5 mg equivalent are needed 7.
Converting this to oxycodone: 15 tablets of morphine 5 mg = 10 tablets of oxycodone 5 mg (using the 1.5:1 potency ratio) 2, 4. Therefore, 15 tablets of oxycodone 5 mg represents a reasonable 3-5 day supply for acute pain when dosed appropriately every 4-6 hours as needed 1, 7.
Common Prescribing Pitfalls
- Avoid fixed every-8-hour dosing for immediate-release oxycodone in acute pain, as this doesn't match the pharmacokinetic profile and may lead to periods of inadequate analgesia 1, 4
- For chronic cancer pain requiring around-the-clock dosing, immediate-release oxycodone should be given every 4-6 hours, or controlled-release formulations should be used every 12 hours 2, 1, 5
- The prescription as written (every 8 hours) creates a mismatch between dosing interval and drug half-life, potentially compromising pain control 4