How Ketamine Works: NMDA Receptor Antagonist
Ketamine is an anesthetic and is used to facilitate painful surgical procedures. It was first synthesized in 1962 and first became available for use in humans in 1969.
Ketamine is categorized as a dissociative anesthetic. Sensations experienced from the body are not perceived in the conscious mind under its effect. It essentially disconnects the mind from the body, making it useful in surgical and procedural settings since, under ketamine’s pharmacologic influence, pain is not experienced.
Ketamine is a novel anesthetic and works by blocking the N-methyl D-aspartate (NMDA) receptor. In medical jargon, it is an NMDA receptor antagonist. It blocks the effects of glutamate, which is an excitatory neurotransmitter in the brain and spinal cord.
Although ketamine works primarily at the NMDA receptor, it also has opioid receptor, monoamine receptor, and muscarinic receptor activity.
IV ketamine, when administered intravenously, is active within seconds. The half-life is about 2.5 hours and is almost entirely eliminated from the system within 10 hours. Driving a motor vehicle or operating machinery is not advised for 24 hours post-ketamine infusion treatment.
The ketamine infusion treatment can cause nausea (due to rapid eye movements), hallucinations, and abnormalities in perception like double vision. It increases heart rate, blood pressure, and dilates airways, which incidentally can be used to treat asthma by improving bronchospasm and wheezing.
Ketamine is "on-label," FDA-certified, for anesthesia. It is used off-label for chronic neuropathic pain and nerve injury. Examples of these conditions are fibromyalgia, complex regional pain syndrome, reflex sympathetic dystrophy, erythromelalgia, and spinal cord injury.
Ketamine has been shown to be effective to treat depression and posttraumatic stress disorder (PTSD) resistant to other types of treatment. The FDA has approved intranasal ketamine, esketamine, for the treatment of depression. Study of ketamine effectiveness in improving symptoms of depression shows the remission of severe depression in 52% of study participants after just 3 ketamine treatments over a period of 11 days. Another 15% of study participants showed some improvement. Suicidal thoughts were significantly reduced (Parikh 2024).
The benefit of individualized, intravenously administered ketamine treatment is the ability to titrate the dose according to individual response and needs. These IV ketamine treatments are carefully supervised and include vital sign monitoring. The administration protocol is designed by a board-certified anesthesiologist.
The typical ketamine infusion treatment starts with premedication with clonidine to decrease the hypertensive effects of ketamine. It lowers blood pressure. Intravenous antinausea medication and sedatives, benzodiazepines, such as Ativan or Versed are given to reduce the incidence of nausea and anxiety.
A medically supervised ketamine infusion usually takes 60 to 90 minutes. A responsible adult must accompany the patient to the infusion visit, transport them home, and remain with them until the effects of the infusion have dissipated (typically 6 to 10 hours).
Learn more about the Ketamine Infusion program at Advanced Diagnostic Pain Treatment Centers.
Request More Information
Please submit the following form for more information on Ketamine Infusion Therapy for Chronic Pain or Depression. One of our patient coordinators will reach out to you by phone or email as soon as possible.