Esketamiini

Esketamiini is the S-enantiomer of ketamine, a dissociative anesthetic with antidepressant properties. In medicine it is formulated as a nasal spray and is used as an adjunct to an oral antidepressant for adults with certain depressive disorders. It is not prescribed as a stand‑alone antidepressant.

Pharmacology and mechanism of action are not fully understood, but esketamiini acts as a noncompetitive antagonist of the NMDA receptor, a central component of the glutamatergic system. This interaction is thought to trigger a rapid cascade of glutamate signaling, leading to synaptic changes and faster antidepressant effects than traditional therapies. The nasal formulation provides rapid systemic absorption, and esketamiini is metabolized in the liver with metabolites excreted in urine.

Medical uses and approval status vary by country. In many jurisdictions esketamiini nasal spray is approved for adults with treatment‑resistant depression, used in combination with a standard oral antidepressant. Some regulatory bodies have extended indications to include acute depressive symptoms with suicidal ideation or behavior, under stringent clinical supervision. It is not a first‑line treatment and is intended for patients who have not responded adequately to other therapies.

Administration and safety require close medical supervision. Dosing is in milligrams per spray with regimens typically involving twice‑weekly administrations during an initial period, followed by less frequent dosing based on response. Patients are monitored for at least several hours after dosing due to risks of dissociation, sedation, dizziness, and transient increases in blood pressure. Esketamiini is a controlled substance in many countries due to potential for abuse and dependence, and it is usually dispensed only in certified clinics.