Interventional psychiatry (Part 1)

Ketamine is a schedule III medication with addictive properties. Delirium, panic attacks, hallucinations, nightmares, dysphoria, and paranoia may occur during and after use.¹³ Premedication with benzodiazepines, most notably lorazepam, is occasionally used to minimize ketamine’s adverse effects, but this generally is not recommended because doing so reduces ketamine’s antidepressant effects.¹⁴ Driving and operating heavy machinery is contraindicated after IV infusion. The usual protocol involves an IV infusion of ketamine 0.4 mg/kg to 1 mg/kg dosing over 1 hour. Doses between 0.4 mg/kg and 0.6 mg/kg are most common. Ketamine has a therapeutic window; doses >0.5 mg/kg are progressively less effective.¹⁵ Unlike the recommendation after esketamine administration, after receiving ketamine, patients remain in the care of their treatment team for <2 hours.

Esketamine, the S enantiomer of ketamine, was FDA-approved for TRD as an intranasal formulation. Esketamine is more commonly used than IV ketamine because it is FDA-approved and typically covered by insurance, but it may not be as effective.¹⁶ An economic analysis by Brendle et al¹⁷ suggested insurance companies would lower costs if they covered ketamine infusions vs intranasal esketamine.

Aducanumab and lecanemab

The most recent FDA-approved interventional agents are aducanumab and lecanemab, which are indicated for treating Alzheimer disease.^18,19 Both are human monoclonal antibodies that bind selectively and with high affinity to amyloid beta plaque aggregates and promote their removal by Fc receptor–mediated phagocytosis.²⁰

FDA approval of aducanumab and lecanemab was controversial. Initially, aducanumab’s safety monitoring board performed a futility analysis that suggested aducanumab was unlikely to separate from placebo, and the research was stopped.²¹ The manufacturer petitioned the FDA to consider the medication for accelerated approval on the basis of biomarker data showing that amyloid beta plaque aggregates become smaller. Current FDA approval is temporary to allow patients access to this potentially beneficial agent, but the manufacturer must supply clinical evidence that the reduction of amyloid beta plaques is associated with desirable changes in the course of Alzheimer disease, or risk losing the approval.

Lecanemab is also a human monoclonal antibody intended to remove amyloid beta plaques that was FDA-approved under the accelerated approval pathway.²² Unlike aducanumab, lecanemab demonstrated a statistically significant (although clinically imperceptible) reduction in the rate of cognitive decline; it did not show cognitive improvement.²³ Lecanemab also significantly reduced amyloid beta plaques.²³

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