The treatment of depressive episodes remains complicated by the long latency of antidepressant efficacy, insufficient response, and high risk of suicide. Ketamine and esketamine have been proposed as fast-acting substances able to overcome these impediments.Since the first randomized controlled trial in the year 2000, numerous studies have explored the antidepressant efficacy of ketamine and esketamine. Clear evidence has emerged that a single infusion exerts a significant antidepressant and antisuicidal effect in both unipolar and bipolar depression. A few studies suggest that antidepressant response can be improved and maintained by repeated administration. Although intravenous application has been most common, subcutaneous, intramuscular, and intranasal application has also been successful. There is some evidence that ketamine may accelerate the response to electroconvulsive therapy without improving the overall response rate.The precise position of ketamine and esketamine within treatment algorithms have yet to be defined, and issues surrounding potential toxicity need to be resolved.

Rationale Ketamine is the first widely used substance with rapid-onset antidepressant action. However, there are uncertainties regarding its potential urothelial toxicity, particularly after repeated application. In the context of rising recreational ketamine use, severe side effects affecting the human urinary tract have been reported. It is assumed that ketamine interacts with bladder urothelial cells and induces apoptosis. Objectives This study aimed to assess whether single or repeated doses of esketamine used in an antidepressant indication are associated with urinary toxicity. Methods We included male and female inpatients with a current episode of depression and a diagnosis of recurrent depressive disorder, bipolar disorder or schizoaffective disorder according to ICD-10 criteria (n = 25). The esketamine treatment schedule involved a maximum of 3× weekly dosing at 0.25–0.5 mg/kg i.v. or s.c. The primary outcome was the change in urine toxicity markers (leukocytes, erythrocytes, protein and free haemoglobin). Description of demographic, clinical and laboratory data was conducted using means, standard deviations, frequencies and percentages. Changes in urinary toxicity markers over time were evaluated using linear mixed models with gender as a covariate. Results The participants received an average of 11.4 (SD 8) esketamine treatments, and an average number of 11.2 (SD 8) urine samples were analysed over the course of treatment. Neither urinary leukocyte concentration (F(20; 3.0) = 3.1; p = 0.2) nor erythrocyte concentration (F(20;2.2) = 4.1; p = 0.2) showed a significant trend towards increase during the course of esketamine treatment. Similarly, free haemoglobin and protein concentrations, which were analysed descriptively, did not display a rise during treatment. There was a significant improvement in depression ratings after esketamine treatment (p < 0.001). Conclusions This study is, to the best of our knowledge, the first to focus on urothelial toxicity of esketamine used in antidepressant indication and dose. The results indicate that the use of single or repeated doses of esketamine is unlikely to cause urothelial toxicity. The results are in need of confirmation as sample size was small.

Background (Es)ketamine and monoamine oxidase inhibitors (MAOIs), e.g., tranylcypromine, are therapeutic options for treatment-resistant major depression. Simultaneous administration is currently not recommended because of concern about hypertensive crises. Objective Our objective was to evaluate whether changes in systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) during esketamine administration differed between patients who concomitantly received tranylcypromine and those who did not. Methods This was a retrospective cohort study utilizing cardiovascular monitoring data from inpatients treated for severe depression in unipolar, bipolar, and schizoaffective disorder. Primary outcomes were change in mean BP and HR during the first hour after intravenous or subcutaneous esketamine administration compared with baseline, controlled for confounders. Secondary analyses quantify differences in absolute BP during esketamine treatment and comparisons of BP peaks, temporal effects, and intraindividual comparisons before and after tranylcypromine initiation. Results Our analysis included 509 esketamine administrations in 43 patients, 14 of whom concomitantly received tranylcypromine. Controlling for creatinine and age, mean ± standard deviation (SD) BP changes were significantly increased by concomitant tranylcypromine treatment (ΔSBP: F[1,503] = 86.73, p < 0.001; ΔDBP: F[1,503] = 55.71, p < 0.001), but HR remained unaffected. Mean SBP change during esketamine administration was 2.96 ± 18.11 mmHg in patients receiving tranylcypromine (TCP+) and −8.84 ± 11.31 mmHg in those who did not (TCP−). Changes in DBP were −2.81 ± 11.20 mmHg for TCP+ and −10.77 ± 9.13 mmHg for TCP−. Moreover, we found a significant dose-response relationship between tranylcypromine dose and BP (SBP: B = 0.35, standard error [SE] = 0.12, 95% confidence interval [CI] 0.12-0.60, p = 0.004; adjusted R 2 = 0.11, p = 0.008; DBP: B = 0.21, SE = 0.08, 95% CI 0.06-0.36, p = 0.007; adjusted R 2 = 0.08; p = 0.023). Conclusions Although statistically significant changes in BP were identified in patients receiving tranylcypromine and esketamine, these changes were clinically insignificant. Thus, combining esketamine and this MAOI appears to be safe at standard doses. The dose-response relationship calls for caution with higher doses of tranylcypromine.