Correction: Double-blind, placebo-controlled, dose-ranging trial of intravenous ketamine as adjunctive therapy in treatment-resistant depression (TRD).

Supplementary Figure 1 and Supplementary Tables 1-4 have been re-uploaded so as to reflect the versions supplied during proofs stage. The publisher apologizes for the error in versioning. The HTML version of the paper has been updated.

Double-blind, placebo-controlled, dose-ranging trial of intravenous ketamine as adjunctive therapy in treatment-resistant depression (TRD).

Numerous placebo-controlled studies have demonstrated the ability of ketamine, an NMDA receptor antagonist, to induce rapid (within hours), transient antidepressant effects when administered intravenously (IV) at subanesthetic doses (0.5 mg/kg over 40 min). However, the optimal antidepressant dose remains unknown. We aimed to compare to active placebo the rapid acting antidepressant properties of a broad range of subanesthetic doses of IV ketamine among outpatients with treatment-resistant depression (TRD). A range of IV ketamine doses were compared to active placebo in the treatment of adult TRD over a 3-day period following a single infusion over 40 min. This was an outpatient study conducted across six US academic sites. Outpatients were 18-70 years old with TRD, defined as failure to achieve a satisfactory response (e.g., less than 50% improvement of depression symptoms) to at least two adequate treatment courses during the current depressive episode. Following a washout period, 99 eligible subjects were randomly assigned to one of the five arms in a 1:1:1:1:1 fashion: a single intravenous dose of ketamine 0.1 mg/kg (n = 18), a single dose of ketamine 0.2 mg/kg (n = 20), a single dose of ketamine 0.5 mg/kg (n = 22), a single dose of ketamine 1.0 mg/kg (n = 20), and a single dose of midazolam 0.045 mg/kg (active placebo) (n = 19). The study assessments (HAM-D-6, MADRS, SDQ, PAS, CGI-S, and CGI-I) were performed at days 0, 1, 3 (endpoint), 5, 7, 14, and 30 to assess the safety and efficacy. The overall group × time interaction effect was significant for the primary outcome measure, the HAM-D-6. In post hoc pairwise comparisons controlling for multiple comparisons, standard dose (0.5 mg/kg) and high dose (1 mg/kg) of intravenous ketamine were superior to active placebo; a low dose (0.1 mg/kg) was significant only prior to adjustment (p = 0.02, p-adj = 0.14, d = -0.82 at day 1). Most of the interaction effect was due to differences at day 1, with no significant adjusted pairwise differences at day 3. This pattern generally held for secondary outcomes. The infusions of ketamine were relatively well tolerated compared to active placebo, except for greater dissociative symptoms and transient blood pressure elevations with the higher doses. Our results suggest that there is evidence for the efficacy of the 0.5 mg/kg and 1.0 mg/kg subanesthetic doses of IV ketamine and no clear or consistent evidence for clinically meaningful efficacy of lower doses of IV ketamine. Trial Registration: NCT01920555.

Double-blind, placebo-controlled, proof-of-concept trial of a kappa-selective opioid receptor antagonist augmentation in treatment-resistant depression.

BACKGROUND: Kappa-opioid antagonism may possess antidepressant properties. We assessed, in a proof-of-concept pilot trial among patients with major depressive disorder with inadequate response to antidepressants, the efficacy of adjunctive CERC-501 (formerly LY2456302), a kappaselective opioid receptor antagonist. METHODS: In a Sequential Parallel Comparison Design study, patients were pre-randomized to: a) 10 mg/d of CERC-501 for 6 days, b) 20 mg/d of CERC-501 for 6 days, c) placebo for 3 days followed by 10 mg/d of CERC- 501 for 3 days, d) placebo for 3 days followed by 20 mg/d of CERC-501 for 3 days, or e) placebo for 6 days. RESULTS: The study was terminated early by the National Institute of Mental Health due to slow enrollment (N = 8). The weighted mean difference of changes (drug vs placebo) in the 6-item Hamilton Depression Rating Scale (HAMD-6) (primary outcome measure) (1.28), Montgomery-Åsberg Depression Rating Scale (MADRS) (2.33), Perceived Stress Scale (1.01), Symptoms of Depression Questionnaire (9.17), Positive Affect Scale (PAS) (6.39), Symptom Questionnaire (SQ) Depression scale (2.94), SQ Anger- Hostility scale (1.67), and Patient-Reported Outcomes Measurement Information System Satisfaction with Participation in Discretionary Social Activities (4.67) scores were all numerically but not statistically greater for CERC-501 than for placebo. CONCLUSIONS: Although the small sample size limits the ability to draw conclusions, results suggest that CERC-501 may have antidepressant effects. Additional studies are necessary to further explore these effects of CERC-501.

Efficacy of intravenous ketamine treatment in anxious versus nonanxious unipolar treatment-resistant depression.

OBJECTIVE: To examine the effect of high baseline anxiety on response to ketamine versus midazolam (active placebo) in treatment-resistant depression (TRD). METHODS: In a multisite, double-blind, placebo-controlled trial, 99 subjects with TRD were randomized to one of five arms: a single dose of intravenous ketamine 0.1, 0.2, 0.5, 1.0 mg/kg, or midazolam 0.045 mg/kg. The primary outcome measure was change in the six-item Hamilton Rating Scale for Depression (HAMD6). A linear mixed effects model was used to examine the effect of anxious depression baseline status (defined by a Hamilton Depression Rating Scale Anxiety-Somatization score ≥7) on response to ketamine versus midazolam at 1 and 3 days postinfusion. RESULTS: N = 45 subjects had anxious TRD, compared to N = 54 subjects without high anxiety at baseline. No statistically significant interaction effect was found between treatment group assignment (combined ketamine treatment groups versus midazolam) and anxious/nonanxious status on HAMD6 score at either days 1 or 3 postinfusion (Day 1: F(1, 84) = 0.02, P = 0.88; Day 3: F(1, 82) = 0.12, P = 0.73). CONCLUSION: In contrast with what is observed with traditional antidepressants, response to ketamine may be similar in both anxious and nonanxious TRD subjects. These pilot results suggest the potential utility of ketamine in the treatment of anxious TRD.

Guarding the Gate: Remote Structured Assessments to Enhance Enrollment Precision in Depression Trials.

BACKGROUND: Failed treatment trials are common in major depressive disorder and treatment-resistant depression, and remotely performed multifaceted, centralized structured interviews can potentially enhance signal detection by ensuring that enrolled patients meet eligibility criteria. METHODS: We assessed the use of a specific remote structured interview that validated the diagnosis, level of treatment resistance, and depression severity. The objectives were to (1) assess the rate at which patients who were deemed eligible for participation in trials by site investigators were ineligible, (2) assess the reasons for ineligibility, (3) compare rates of ineligibility between academic and nonacademic sites, (4) compare eligibility between US and non-US sites, and (5) report the placebo response rates in trials utilizing this quality assurance approach, comparing its placebo response rates with those reported in the literature. Methods included a pooled analysis of 9 studies that utilized this methodology (SAFER interviews). RESULTS: Overall, 15.33% of patients who had been deemed eligible at research sites were not eligible after the structured interviews. The most common reason was that patients did not meet the study requirements for level of treatment resistance. Pass rates were significantly higher at non-US compared with US sites (94.6% vs 83.3%, respectively; P < 0.001). There was not a significant difference between academic and nonacademic sites (87.8% vs 82.4%; P = 0.08). Placebo response rates were 13.0% to 27.3%, below the 30% to 40% average in antidepressant clinical trials, suggesting a benefit of the quality assurance provided by these interviews. CONCLUSIONS: The use of a remotely structured interview by experienced clinical researchers was feasible and possibly contributed to lower-than-average placebo response rates. The difference between US and non-US sites should be the subject of further research.

A double-blind, placebo-controlled study of aripiprazole adjunctive to antidepressant therapy among depressed outpatients with inadequate response to prior antidepressant therapy (ADAPT-A Study).

BACKGROUND: We assessed the efficacy of low-dose aripiprazole added to antidepressant therapy (ADT) in major depressive disorder (MDD) patients with inadequate response to prior ADT. METHODS: As per the sequential parallel comparison design, 225 MDD subjects were randomized to adjunctive treatment with aripiprazole 2 mg/day or placebo across two 30-day phases, with a 2:3:3 randomization ratio to drug/drug (aripiprazole 2 mg/day in phase 1; 5 mg/day in phase 2), placebo/placebo (placebo in both phases), and placebo/drug (placebo in phase 1; aripiprazole 2 mg/day in phase 2). Eligible subjects were patients whose MDD was independently deemed 'valid' with SAFER criteria. Subjects had been receiving ADT for ≥8 weeks, and had inadequate response to ≥1 and <4 adequate ADTs in the current episode, as defined by the Antidepressant Treatment Response Questionnaire. RESULTS: The pooled, weighted response difference between aripiprazole 2 mg/day and placebo in the two phases was 5.6% (p = 0.18; NS). The aripiprazole 2 mg/day-placebo difference on the Montgomery-Asberg Depression Rating Scale pooled across the two phases was -1.51 (p = 0.065; NS). Other secondary endpoint analyses showed nonsignificant pooled differences favoring aripiprazole over placebo. Of the 225 randomized subjects in phase 1, 2 dropped out in both arms, while in phase 2, of 138 phase 1 placebo nonresponders, 9 dropped out on aripiprazole and 5 on placebo. There were only minimal differences in adverse event rates between treatments, except for constipation, weight gain, and dry mouth, more common on aripiprazole. CONCLUSIONS: This study provides clear support for the tolerability of low-dose aripiprazole as an ADT-augmenting agent, with marginal efficacy.

Effect of Concomitant Benzodiazepines on the Antidepressant Effects of Ketamine: Findings From the RAPID Intravenous Ketamine Study.

Objective: Ketamine is a novel and rapidly acting treatment for major depressive disorder (MDD). Benzodiazepines are commonly coprescribed with antidepressants in MDD. This study sought to examine data from a randomized clinical trial that compared a single infusion of intravenous (IV) ketamine to midazolam placebo in treatment-resistant depression (DSM-IV-TR MDD) and to assess whether the use of concomitant oral benzodiazepines differentially affected treatment response to ketamine versus midazolam.Methods: This trial ran from December 2015 to December 2016. Subjects who were taking oral benzodiazepines (n = 44) were compared to those who were not (n = 55). A significant treatment-by-benzodiazepine effect could be interpreted as a possible moderator of differential treatment response to ketamine versus midazolam. Benzodiazepine use was examined as both a binary and a continuous predictor, to assess the impact of dosage.Results: Benzodiazepine users did not differ from non-users on the original study's primary outcome measure, score on the 6-item Hamilton Depression Rating Scale (HDRS-6), at baseline, but the former had more severe anxiety. When oral benzodiazepine use was modeled as a binary predictor, benzodiazepine use did not impact differential treatment response. However, when benzodiazepine dosage was considered, there was a significant impact of benzodiazepine use on differential treatment response. Oral benzodiazepines significantly impacted HDRS-6 (P = .018) and Clinical Global Impressions-Severity of Illness scale (CGI-S; P = .008) scores at day 1 (24 hours post treatment); effects were nonsignificant for all day 3 outcomes. Among ketamine subjects, higher doses of benzodiazepines were associated with less improvement in depression scores at day 1.Conclusions: Concomitant oral benzodiazepines at higher doses may attenuate the antidepressant effects of IV ketamine at day 1 but not day 3 post-infusion.Trial Registration: ClinicalTrials.gov identifier: NCT01920555.

The effect of single administration of intravenous ketamine augmentation on suicidal ideation in treatment-resistant unipolar depression: Results from a randomized double-blind study.

This study aimed to assess the effect of a single infusion of intravenous (IV) ketamine on suicidal ideation in patients with treatment-resistant depression (TRD). Patients with TRD were randomized in a double-blind fashion to a single infusion of IV ketamine or IV midazolam placebo. Suicidal ideation was measured using the Montgomery-Asberg Depression Rating Scale (MADRS) suicide item at 3, 5, 7, 14 and 30 days post infusion. Clinically significant suicidal ideation was defined as a MADRS suicide item score ≥2. Forty patients who received IV ketamine and 16 who received IV midazolam had suicide item scores of ≥2 at baseline (IV ketamine group mean 2.90±0.74; IV midazolam group 2.69±0.70). The mean suicide scores of these groups differed significantly from each other on day 30; the IV ketamine group had a lower mean score than controls (2.03±1.59 vs. 3.00±1.41, t-test p = 0.049; Hedges' g 0.71). Among patients with a suicide score of ≥2 at baseline and <2 at day 3, the two groups did not differ significantly on mean scores changes at days 3, 5, 7, 14 or 30. Recurrence of suicidal ideation was extensive in both treatment groups. A single infusion of IV ketamine may reduce suicidal ideation in TRD out to 30 days post infusion, but early anti-suicidal effects appear to diminish rapidly. This post-hoc analysis was not powered to compare different doses of ketamine. A single infusion of IV ketamine might have a role as an adjunct to standard treatments in patients with TRD and suicidal ideation. Trial registration: NCT01920555.

Time to relapse after a single administration of intravenous ketamine augmentation in unipolar treatment-resistant depression.

OBJECTIVE: To examine the rate and time to relapse for remitters and responders to ketamine in treatment-resistant depression (TRD). METHODS: Subjects with TRD were randomized to a single infusion of one of several doses of intravenous ketamine, or midazolam. Using Kaplan-Meier survival function, the current report examines the rate and time to relapse, defined as MADRS ≥ 22, over a period of 30 days, in subjects who achieved remission (MADRS ≤ 10) or response (≥ 50% reduction in MADRS) on day three post-infusion of intravenous ketamine 0.1, 0.5, or 1.0 mg/kg. RESULTS: Of the 60 randomized participants who received a single ketamine (0.1, 0.5, or 1.0 mg/kg) infusion, 19 (34%) met criteria for remission and 27 (48%) for response, on day 3 post-infusion. A numerical dose-response relationship was observed, with remitters/responders on ketamine 1.0 mg/kg having the lowest relapse rate, followed by ketamine 0.5 mg/kg and 0.1 mg/kg, respectively (% of remitters who relapsed by day 14: 38% with 1.0 mg/kg, 50% with 0.5 mg/kg, 100% with 0.1 mg/kg;% of responders who relapsed by day 14: 30% with 1.0 mg/kg, 50% with 0.5 mg/kg, 80% with 0.1 mg/kg). LIMITATIONS: The sample size was small. No MADRS measurements at day one post-infusion. The study was not powered to assess differences in relapse prevention between different doses of ketamine. CONCLUSION: Time to relapse after successful treatment with a single infusion of ketamine appears to follow a dose-response relationship, where higher dosage leads to increased time to relapse.

Double-blind, proof-of-concept (POC) trial of Low-Field Magnetic Stimulation (LFMS) augmentation of antidepressant therapy in treatment-resistant depression (TRD).

BACKGROUND: Low-Field Magnetic Stimulation (LFMS) is a novel, non-invasive, sub-threshold neuromodulation technique, shown in preliminary studies to have immediate mood elevating effects in both unipolar and bipolar depressed patients. OBJECTIVE: We aimed to assess the antidepressant augmentation effects at 48 h of LFMS administered on two consecutive days compared to sham treatment in treatment resistant depression (TRD) subjects, using the Sequential Parallel Comparison Design (SPCD). METHODS: Eighty-four eligible subjects with TRD were randomly assigned to double-blind treatment with LFMS 20 min/day for four days, sham treatment 20 min/day for four days, or sham treatment 20 min/day for 2 days followed by LFMS treatment 20 min/day for two days, using the pre-randomization version of the SPCD (randomization 1:1:1). The SPCD analyses used a repeated measures linear modeling approach with maximum likelihood estimation to use all available data, and using a 60-40 weighting of Stage 1 vs. 2 responses, with the primary outcome being measured after 2 and 4 days. RESULTS: Both primary and secondary outcome measures consistently showed no differences between LFMS-treated patients and those treated with sham, with the exception of a slight, non-significantly greater improvement than sham in the visual analogue scale (VAS) sad mood on LFMS-treated patients. LFMS treatment was relatively well tolerated. CONCLUSIONS: We did not observe a significantly greater, rapid efficacy of LFMS compared to sham therapy. Future studies need to examine the possible therapeutic effects of more intensive forms of LFMS, as other forms of neurostimulation typically require longer duration of exposure.