Ketamine + Esketamine

Ketamine and esketamine are closely related drugs with similar but distinct properties. Esketamine is the S(+) enantiomer of ketamine, meaning it's one of the two mirror-image molecules that make up racemic ketamine. While ketamine has been used as an anesthetic since 1970, esketamine received FDA approval for treatment-resistant depression in 2019 as a nasal spray (Spravato). ## Pharmacology and Mechanism of Action Both ketamine and esketamine function primarily as NMDA receptor antagonists, though esketamine is more potent in this regard than racemic ketamine. This mechanism differs from traditional antidepressants and explains their rapid onset of action, which can provide relief within hours rather than weeks. Esketamine is specifically approved for: - Treatment-resistant depression (TRD) in adults - Major depressive disorder (MDD) with suicidal ideation or behavior Ketamine, while FDA-approved only as an anesthetic, is used off-label for depression, pain management, and other psychiatric conditions. ## Administration and Dosing Esketamine is administered as a nasal spray under direct medical supervision, with patients requiring monitoring for at least two hours after administration due to potential side effects. The typical regimen involves twice-weekly administration for the first month, followed by once weekly or once every two weeks thereafter. Ketamine for depression is typically administered intravenously at sub-anesthetic doses, though this use remains off-label. ## Side Effects and Safety Considerations Common side effects of both drugs include: - Dissociation - Dizziness - Sedation - Nausea - Increased blood pressure - Feelings of drunkenness Due to these effects, patients should not drive or operate machinery until the next day after treatment. Both drugs carry potential risks for those with unstable hypertension or vascular disorders. ## Clinical Evidence Studies have demonstrated that esketamine provides meaningful decreases in depression scores compared to placebo, with benefits for both short-term treatment and longer-term maintenance. Unlike most antidepressants, esketamine has been shown to decrease suicidal thoughts rather than potentially increasing them during initial treatment. The combination of ketamine and esketamine represents an important advancement in treating depression, particularly for patients who haven't responded to conventional treatments[1][2][5][6][9].