Oxycodone to Tramadol Conversion Dosing
When converting from oxycodone to tramadol, use a conversion ratio of approximately 1:7.5, with a recommended starting dose of tramadol 50-100 mg every 4-6 hours, not to exceed 400 mg daily. 1, 2
Conversion Calculation
- Based on morphine milligram equivalent (MME) conversion factors, tramadol has a potency of 0.2 compared to morphine, while oxycodone has a potency of 1.5 compared to morphine 1
- This creates an approximate conversion ratio of 7.5:1 (tramadol:oxycodone) 1
- Practical conversion examples:
Dosing Strategy
- Start tramadol at 50 mg once or twice daily and increase gradually as needed to a maximum of 400 mg/day 3, 2
- For patients requiring rapid onset of analgesic effect, tramadol 50-100 mg can be administered every 4-6 hours, not exceeding 400 mg daily 2
- For patients not requiring rapid onset, initiate with a titration regimen to improve tolerability:
Special Populations
- For patients with creatinine clearance <30 mL/min: increase dosing interval to 12 hours with maximum daily dose of 200 mg 2
- For patients with cirrhosis: 50 mg every 12 hours 2
- For elderly patients (>65 years): start at the low end of the dosing range 2
- For elderly patients (>75 years): total dose should not exceed 300 mg/day 2
Important Considerations
- Tramadol is a weak μ-opioid agonist that also inhibits reuptake of serotonin and norepinephrine 3, 4
- Tramadol has a lower risk of abuse compared to oxycodone and other strong opioids 3, 4
- Tramadol is considered a second-line medication for neuropathic pain but may be used as first-line in certain circumstances (acute neuropathic pain, cancer pain, episodic severe pain) 3
- The analgesic effect of tramadol begins within one hour and peaks in approximately two hours 5
Adverse Effects and Monitoring
- Common adverse effects include dizziness, nausea, vomiting, dry mouth, constipation, and sedation 5
- Tramadol lowers the seizure threshold and can interact with SSRIs and SNRIs to cause serotonin syndrome 3
- Adverse effects are dose-dependent, particularly nausea, so starting with lower doses during the first days of treatment improves tolerability 4, 6
- Monitor for signs of respiratory depression, though this is generally less severe than with strong opioids 4
Pharmacogenetic Considerations
- CYP2D6 genotype affects tramadol metabolism and efficacy 7
- For CYP2D6 ultra-rapid metabolizers, consider decreasing the dose to 40% of the commonly prescribed dose or use an alternative analgesic 7
- For CYP2D6 poor metabolizers or intermediate metabolizers with insufficient analgesia, consider an alternative analgesic not metabolized by CYP2D6 7
By following these guidelines for converting from oxycodone to tramadol, clinicians can provide effective pain management while minimizing adverse effects and considering individual patient factors.