From the Research
Ketamine dosing for Complex Regional Pain Syndrome (CRPS) should involve intravenous infusions at subanesthetic doses, with a recent study suggesting doses ranging from 0.1-1.0 mg/kg/hour, administered over 4-6 hours for 3-5 consecutive days 1.
Key Considerations
- A common starting protocol is 0.5 mg/kg delivered over 4 hours, which may be repeated weekly or monthly depending on response.
- For outpatient management, oral ketamine can be prescribed at 10-30 mg three times daily, though this route has less evidence supporting its efficacy.
- Intranasal ketamine at 10-50 mg per dose is another alternative for breakthrough pain.
- Treatment should be initiated and monitored by pain specialists due to potential side effects including dissociation, hallucinations, elevated blood pressure, and nausea.
Mechanism and Efficacy
- Ketamine works by modulating NMDA receptors to reduce central sensitization and wind-up phenomena that contribute to CRPS pain.
- Recent studies, including a systematic review and meta-analysis, have shown that ketamine can provide significant pain relief for CRPS patients, with some studies indicating long-term benefits 1, 2.
Safety and Monitoring
- Long-term ketamine use requires monitoring for urinary tract issues, cognitive effects, and liver function.
- Adverse effects, such as nausea, vomiting, headache, or psychotropic symptoms, can occur but are often mitigated with cessation of the drug.
Individualization of Treatment
- Treatment response varies considerably between patients, so dosing often requires individualization based on efficacy and tolerability.
- A recent narrative review highlights the need for further research to determine optimal dosing and duration of ketamine infusion for CRPS treatment 2.