Yes, a psychiatrist can prescribe ketamine. Ketamine, historically known as an anesthetic, has emerged as a rapid-acting treatment for certain psychiatric conditions, particularly those resistant to conventional therapies. This molecule offers a fundamentally different pathway to relief compared to traditional antidepressants, which typically take weeks to exert their effect. The use of ketamine in mental health is a heavily regulated and specialized area of practice, requiring specific knowledge and protocols to ensure patient safety and therapeutic benefit.
The Scope of Psychiatric Prescribing Authority
Ketamine is classified by the Drug Enforcement Administration (DEA) as a Schedule III controlled substance due to its potential for abuse. Psychiatrists, as licensed medical doctors with prescriptive authority, are legally permitted to prescribe controlled substances like ketamine. The practical application of this authority is split between two distinct forms of the drug.
One form is esketamine, the S-enantiomer of the ketamine molecule, which is FDA-approved under the brand name Spravato. It is indicated for use in conjunction with an oral antidepressant for adults with Treatment-Resistant Depression (TRD), and for depressive symptoms in Major Depressive Disorder (MDD) with acute suicidal ideation. Prescribing Spravato requires that the psychiatrist and the facility they work in are certified and comply with a strict Risk Evaluation and Mitigation Strategy (REMS) program.
The other form, racemic ketamine, is the original mixture of the S- and R-enantiomers and is FDA-approved only as an anesthetic. Psychiatrists often prescribe this form “off-label” for psychiatric conditions, typically administered via intravenous (IV) infusion. This off-label use is a common and legal medical practice when supported by scientific evidence, but it demands the highest level of clinical judgment and patient monitoring, as it is not regulated by the REMS program.
The decision to prescribe either form hinges on the psychiatrist’s specialized training and the clinical context. Training involves understanding the sub-anesthetic dosing required for psychiatric effects, managing potential side effects, and integrating the drug into a comprehensive mental health treatment plan. While any DEA-licensed physician can technically prescribe ketamine, the expertise of a psychiatrist in diagnosis and mental health management makes them ideally suited for this role.
Administration Routes and Necessary Monitoring
The method of delivery is a crucial factor in ketamine treatment, directly influencing the drug’s bioavailability and onset of action. Intravenous (IV) infusion of racemic ketamine is the most common route in specialized clinics, offering the highest level of control over dosage and a near 100% absorption rate. The infusion is typically delivered slowly over 40 to 60 minutes, allowing for real-time dose adjustments based on the patient’s immediate response.
Intramuscular (IM) injection is another route for racemic ketamine, providing a high absorption rate of up to 93% and a rapid onset. However, the psychiatrist has less ability to adjust the dose once it is administered. The FDA-approved esketamine is administered as a self-administered nasal spray under the direct supervision of a healthcare professional in a certified clinic. This route is less invasive but has a lower absorption rate, generally between 20% and 30%.
Oral or sublingual lozenges are also sometimes used, though this route is considered less effective due to poor bioavailability. Regardless of the route, patient safety protocols necessitate rigorous medical monitoring during and immediately following administration. Side effects include transient increases in blood pressure and heart rate, as well as the drug’s characteristic dissociative effects.
For the FDA-approved esketamine nasal spray, the REMS program mandates that patients remain at the treatment center and be monitored by a healthcare professional for at least two hours after administration. Monitoring involves continuous assessment of vital signs, including blood pressure, and observation for any signs of profound sedation or dissociation. The patient is only cleared for discharge once they are clinically stable and a responsible adult is available to transport them home.
Conditions Treated and Therapeutic Mechanisms
Ketamine is primarily utilized for conditions that have not responded to multiple trials of standard psychiatric medications. The most common primary indication is Treatment-Resistant Depression (TRD), which is clinically defined as a failure to achieve a response after two or more different antidepressant trials. Its rapid effect also makes it invaluable for treating Major Depressive Disorder with acute suicidal ideation or behavior, where it can reduce symptoms within hours.
The drug’s therapeutic mechanism represents a significant departure from the monoamine-based theories that underpin most older antidepressants. Ketamine functions as a non-competitive antagonist of the N-methyl-D-aspartate (NMDA) receptor, a type of receptor for the neurotransmitter glutamate. By blocking NMDA receptors, particularly those located on inhibitory GABAergic interneurons, ketamine causes a disinhibition of glutamatergic neurons.
This disinhibition results in a surge of glutamate release into the synapse, which then preferentially activates the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor. Activation of AMPA receptors triggers a cascade of intracellular signaling pathways, most notably the mechanistic Target of Rapamycin (mTOR) pathway and the release of Brain-Derived Neurotrophic Factor (BDNF).
The result of this neurobiological process is a rapid increase in synaptogenesis and synaptic plasticity, which is the growth of new synaptic connections between neurons. The promotion of this neuroplasticity is believed to effectively repair and restore neural network integrity that is compromised in depression, leading to rapid antidepressant effects observed in many patients.