From the Guidelines
Subanesthetic ketamine is typically administered at a dose of 0.5 mg/kg intravenously, infused slowly over 40 minutes, for the treatment of conditions like depression, chronic pain, and PTSD. This dose has been shown to be effective in reducing depressive symptoms and suicidal ideation in patients with treatment-resistant depression (TRD) 1. The most common protocol involves administering this dose 2-3 times per week for 2-3 weeks initially, followed by maintenance treatments as needed.
Administration and Monitoring
Intramuscular administration is sometimes used at similar doses, while oral or intranasal ketamine typically requires higher doses due to lower bioavailability. Subanesthetic doses work by modulating glutamate neurotransmission through NMDA receptor antagonism, which differs from the complete dissociation seen at anesthetic doses (1-2 mg/kg) 1. Treatment should be administered in a monitored setting with vital sign checks due to potential side effects including transient blood pressure elevation, dizziness, and dissociative symptoms.
Patient Selection and Safety
Patients should not drive for 24 hours after treatment, and those with uncontrolled hypertension, unstable cardiac disease, or active psychosis may not be suitable candidates. The effectiveness of ketamine in preventing suicide or reducing suicidal ideation or behavior has not been established, and it is not recommended as an initial treatment but is reserved for patients who have previously not responded to adequate trials of antidepressants 1.
Key Considerations
- Dose: 0.5 mg/kg intravenously, infused slowly over 40 minutes
- Administration frequency: 2-3 times per week for 2-3 weeks initially, followed by maintenance treatments as needed
- Monitoring: vital sign checks due to potential side effects
- Patient selection: caution in patients with uncontrolled hypertension, unstable cardiac disease, or active psychosis
- Mechanism: modulating glutamate neurotransmission through NMDA receptor antagonism 1
From the Research
Subanesthetic Ketamine Dosing
- The dosing for subanesthetic ketamine varies depending on the route of administration and the condition being treated 2, 3, 4, 5, 6.
- For chronic pain, subanesthetic ketamine infusions have been used at various doses, with one study using a continuous intravenous infusion for 7-14 days 2.
- For treatment-resistant depression, oral ketamine has been used at a dose of 1 mg/kg thrice weekly for 21 days 3.
- Subcutaneous ketamine infusions have been used for chronic nonmalignant pain at a subanesthetic dose, with significant reduction in pain intensity and opioid use 5.
- Intravenous ketamine has been used at a subanesthetic dose of 0.5 mg/kg for treatment-resistant depression, with rapid-onset antidepressant properties 6.
Route of Administration
- Subanesthetic ketamine can be administered through various routes, including intravenous, oral, subcutaneous, and intranasal 4.
- Each route of administration has its own advantages and disadvantages, with intravenous administration providing rapid onset of action and oral administration providing convenience and ease of use 3, 4.
- Subcutaneous ketamine infusions have been shown to be well-tolerated and effective for chronic nonmalignant pain 5.
Efficacy and Safety
- Subanesthetic ketamine has been shown to be effective in reducing pain intensity and improving depressive symptoms in patients with chronic pain and treatment-resistant depression 2, 3, 5.
- The safety profile of subanesthetic ketamine is generally considered to be good, with mild and transient side effects such as light-headedness, dizziness, and hallucinations 2, 5.
- However, the long-term safety and efficacy of subanesthetic ketamine require further study, particularly in patients with a history of substance abuse or other mental health conditions 4, 6.