Intranasal esketamine

Pharmacokinetics

Esketamine exposure increases from 28 to 84 mg in a fairly dose-proportional range. No accumulation of esketamine was observed in the plasma following twice-weekly administration. Bioavailability is approximately 48% following nasal administration. The Tmax for esketamine plasma concentration is 20 to 40 minutes after the last nasal spray. Protein binding of esketamine is approximately 43% to 45%. The brain-to-plasma ratio of noresketamine is 4 to 6 times lower than that of esketamine. The half-life of esketamine ranged from 7 to 12 hours. The mean half-life of noresketamine was approximately 8 hours. Esketamine is primarily metabolized to a noresketamine metabolite via cytochrome P450 (CYP) enzymes, 2B6 and 3A4. Noresketamine is metabolized by CYP-dependent pathways and certain metabolites undergo glucuronidation. Drug interaction studies demonstrate that intranasal esketamine had very little effect on pharmacokinetic interactions with other medications.

Potential drug interactions

Central nervous system depressants. Concomitant use of esketamine and other CNS depressants (ie, benzodiazepines, opioids, alcohol) may increase sedation. Patients receiving esketamine with concomitant use of other CNS depressants should be closely monitored for sedation.

Psychostimulants. Concomitant use of esketamine and psychostimulants (ie, amphetamines, methylphenidates, modafinil, and armodafinil) may increase blood pressure. Patients receiving esketamine with concomitant use of psychostimulants should be closely monitored for elevations in blood pressure.

Monoamine oxidase inhibitors. Concomitant use of esketamine with monoamine oxidase inhibitors may increase blood pressure. Closely monitor blood pressure with concomitant use of esketamine and monoamine oxidase inhibitors.

Use in special populations. Because of concerns of increased sedation, intranasal esketamine should be administered cautiously in patients receiving other CNS depressants, such as benzodiazepines. In patients with psychosis or a prior history of psychosis, esketamine should be used with increased caution and the risk/benefit ratio should be carefully considered.

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