Safety and tolerability of IV ketamine in adults with major depressive or bipolar disorder: results from the Canadian rapid treatment center of excellence.

Objectives: Rigorous clinical trials suggest ketamine is safe and well-tolerated in patients with treatment-resistant depression (TRD). There is a paucity of data on the safety and tolerability of ketamine in community-based clinics treating patients with TRD.
Methods: Retrospective data was analyzed from 203 patients with TRD who received repeat-dose IV ketamine. Safety was operationalized as hemodynamic changes. Tolerability was evaluated through the reporting of adverse events and dissociation symptom severity, as measured by the Clinician-Administered Dissociative States Scale.
Results: Ketamine was well-tolerated, with less than 5% of patients withdrawing due to tolerability concerns. Blood pressure significantly increased during infusion, with 44.3% meeting criteria for treatment-emergent hypertension (i.e., blood pressure ≥ 165/100 mmHg). 12% of patients exhibiting hypertension required pharmacological intervention. The most frequently reported adverse events included drowsiness (56.4%), dizziness (45.2%), dissociation (35.6%), and nausea (13.3%). Dissociation severity significantly attenuated after the first infusion, but plateaued for subsequent infusions.
Conclusion: Intravenous ketamine was safe and well-tolerated. Hypertension was commonly observed and was often transient. Dissociation was most frequently reported after the first infusion but remained a consistent but not treatment-limiting adverse event thereafter. No patients exhibited psychosis, mania, or new onset suicidality with IV ketamine.