What is ketamine?
Ketamine is an N-Methyl-D-aspartate (NMDA) receptor antagonist which has been in use since the 1960s as an anaesthetic for children and adults. It therefore has a long track record for safety. During treatment, the medication is administered intravenously (intranasal or sublingual administration are still being studied).
When used in much lower doses than for anaesthesia, ketamine has a powerful antidepressant effect which has only recently been identified and is currently being extensively investigated.
The precise mechanism of the antidepressant action is still being unravelled since the NMDA antagonism does not seem to fully explain the effect observed. Ketamine also appears to increase the levels of dopamine, noradrenaline and serotonin in the brain. It is associated with various biochemical pathways involved in synaptic plasticity. It induces rapid modifications in the presynaptic mechanism of the hippocampus which are similar to those observed after traditional treatment for chronic depression.
Ketamine’s antidepressant action appears within a few hours compared to the several weeks needed for traditionally used medication against depression.
The treatment should not however be considered as a “cure” for depression but as an adjuvant to consolidating other biological or psychological therapies.
Ketamine is also indicated for some conditions of chronic pain and is extremely effective.
Who should use ketamine?
Intravenous ketamine infusions are indicated for patients with severe major depression (unipolar or bipolar) without psychotic symptoms and for various conditions of chronic pain.
It is contraindicated in the case of schizophrenia, psychosis or epilepsy.
Even a single dose of ketamine is a powerful deterrent against suicidal tendencies.
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Is ketamine effective?
An antidepressant is effective for about 50% of the time in a depressive patient, but this probability decreases significantly if a prior therapy failed.
In the case of treatment-resistant depression, the observed response rates with ketamine are especially high, in the range of 50 to 70%, and 30% of patients achieve a full remission.
Although ketamine acts more rapidly than other types of antidepressant treatments, there is an equivalent risk of relapse after a single infusion. This is why infusions need to be repeated. A few patients will start to feel a difference immediately after the first infusion, however fluctuations of mood of sadness or depression are possible between infusions.
A total of 10 infusions will be recommended over a period of 10 weeks in order to bolster the antidepressant effect and avoid sudden relapses. The benefits of such a protocol are normally sustained over an average of 4 weeks.
Subsequently, “booster” infusions can be administered at variable frequency, depending on the evolution of the condition.
If no positive response is observed after five infusions, the protocol is interrupted and other therapies may be suggested.
In all cases, a medical expert is constantly present and can intervene appropriately. All prospective patients have to undergo a medical examination with both a psychiatrist and an anaesthetist to determine if the treatment can be done. Patients with severe cardiovascular or respiratory problems may need further tests before the first infusion or a modification of the treatment. Safety is a primordial consideration at the Centre for Interventional Psychiatry and no treatment is undertaken if the medical team has any apprehension or the risk of complications is unusually high.
The treatment is performed at the Centre for Interventional Psychiatry by a team of highly qualified and experienced anaesthetists. A specialist nurse in anaesthetics or a doctor are present throughout the procedure. A psychiatrist or psychiatric nurse is also constantly available. The patient is installed in a comfortable dimly-lit room and can listen to soft music. External stimuli have to be reduced to a minimum during the time the infusion is done.
Once the infusion starts, vital parameters such as blood pressure, oxygen saturation and the electrocardiogram are constantly monitored. Each infusion lasts approximately 45 minutes and continues to be monitored for at least 30 minutes afterwards.
Most patients describe the experience as a “surprise”. Immediately after the infusion, some patients will briefly experience great well-being while others may feel somewhat confused. This clears up rapidly. Expert medical care is constantly available and will intervene should it be necessary.
Before each infusion, it is imperative that the patient has an empty stomach from six hours before for solid food and three hours for liquids. Consumption of alcohol or other illegal substances is obviously not permissible.
After each infusion, the patient must be accompanied back home and must not drive for 48 hours.
What are the side effects and the risks?
The most common side effects are dizziness, blurred vision, hypertension, tachycardia or nausea. Dissociative effects are frequently observed such as perturbation of functions that are normally integrated- consciousness, memory, identity or perception of the surroundings (for example, being detached-from-the-body feeling), sleepiness or sometimes hallucinations. All these reactions can happen during the infusion. They are monitored and controlled as necessary by specific medication. Side effects disappear quickly on their own when the procedure ends.
The dosage used in depression therapy is significantly lower to the one used for anaesthesia in surgery, for example.
Interactions with other drugs
Any ongoing antidepressant treatment does not need to stop. Ketamine can be given with all types of antidepressants even lithium. Ketamine provides rapid improvement while waiting for the effect of standard medication to set in.
However, there may be reduced benefits with some benzodiazepines (Temesta, Xanax, Lexotanil, etc.) or some antiepileptic drugs (lamotrigine).
Ketamine addiction risk
Although ketamine is used as a recreational drug, it does not qualify as being physically addictive. Prolonged recourse to ketamine can lead to tolerance.
Is ketamine reimbursed by insurance?
Ketamine infusions are not reimbursed by either basic or complementary insurance schemes in Switzerland.
The patient has to meet the entire cost of treatment as well as of the monitoring by specialists in psychiatry and anaesthesia.
More information on costs and payment terms is available upon request.
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