A phase 2 trial of inhaled nitrous oxide for treatment-resistant major depression.

Nitrous oxide at 50% inhaled concentration has been shown to improve depressive symptoms in patients with treatment-resistant major depression (TRMD). Whether a lower concentration of 25% nitrous oxide provides similar efficacy and persistence of antidepressant effects while reducing the risk of adverse side effects is unknown. In this phase 2 clinical trial (NCT03283670), 24 patients with severe TRMD were randomly assigned in a crossover fashion to three treatments consisting of a single 1-hour inhalation with (i) 50% nitrous oxide, (ii) 25% nitrous oxide, or (iii) placebo (air/oxygen). The primary outcome was the change on the Hamilton Depression Rating Scale (HDRS-21). Whereas nitrous oxide significantly improved depressive symptoms versus placebo (P = 0.01), there was no difference between 25 and 50% nitrous oxide (P = 0.58). The estimated differences between 25% and placebo were -0.75 points on the HDRS-21 at 2 hours (P = 0.73), -1.41 points at 24 hours (P = 0.52), -4.35 points at week 1 (P = 0.05), and -5.19 points at week 2 (P = 0.02), and the estimated differences between 50% and placebo were -0.87 points at 2 hours (P = 0.69), -1.93 points at 24 hours (P = 0.37), -2.44 points at week 1 (P = 0.25), and -7.00 points at week 2 (P = 0.001). Adverse events declined substantially with dose (P < 0.001). These results suggest that 25% nitrous oxide has comparable efficacy to 50% nitrous oxide in improving TRMD but with a markedly lower rate of adverse effects.

Efficacy of Esketamine Augmentation in Major Depressive Disorder: A Meta-Analysis.

OBJECTIVE: Esketamine, the S-enantiomer of ketamine, was recently approved as a rapid-acting intranasal therapy for depression and is currently under development for suicidality. The authors sought to determine the efficacy of adjunctive intranasal esketamine in major depressive disorder (MDD). DATA SOURCES: A systematic search of PubMed/MEDLINE was conducted up to January 2019, in addition to abstracts of major psychiatric meetings held since 2010. Searches were conducted by cross-referencing the term intranasal with the term esketamine. Where necessary, authors and/or study sponsors were contacted in order to obtain a copy of the presentation as well as any pertinent study details. STUDY SELECTION: 241 study abstracts were initially identified and reviewed. Selected studies were randomized, double-blind clinical trials comparing adjunctive intranasal esketamine to adjunctive placebo for MDD. DATA EXTRACTION: Data were extracted independently by two of the authors. A random effects model was used to calculate the standardized mean difference (SMD) between esketamine and placebo (intranasal saline) in the Montgomery-Asberg Depression Rating Scale (MADRS) score change from baseline to endpoint, serving as the primary outcome of the study. RESULTS: Five trials with 774 patients were pooled. Adjunctive esketamine was significantly more effective than placebo for MADRS score change, response, and remission (N = 774, SMD = 0.36, 95% CI = 0.24-0.49, P < .0001; response: risk ratio [RR] = 1.40, 95% CI = 1.22-1.61, P < .0001; remission: RR = 1.45, 95% CI = 1.20-1.75, P < .0001). Results remained statistically significant regardless of differences in the study sample, fixed vs new/optimized baseline antidepressants. CONCLUSIONS: Adjunctive intranasal esketamine for patients with MDD who are either treatment-resistant or acutely suicidal appears to be an effective treatment strategy.

Success and efficiency of phase 2/3 adjunctive trials for MDD funded by industry: a systematic review.

To review the success rate and efficiency of industry-sponsored phase 2/3 clinical trials for adjunctive therapies for antidepressant partial- and non-responders with major depressive disorder (MDD), a systematic search of Pubmed/Medline was conducted, in addition to abstracts of major psychiatric meeting held since 2010, of randomized, placebo-controlled adjunct oral pharmacotherapy trials in this patient population. Forty-six (n = 33,900; 70 drug compactor arms) trials were pooled, yielding only three approved drugs. Twenty-two (31.4%) drug-placebo comparisons were successful. Numerically, success rates for treatment arms from studies with one versus more than one drug-placebo comparison were higher (39.3% versus 26.2%). The antidepressant lead-in employing single-blind placebo and the sequential-parallel comparison design (SPCD) were successful in 50% and 40% of cases, respectively. The direct randomization (no lead-in) design yielded positive results in one third of cases. The success rate of open-label antidepressant lead-ins without placebo or using double-blind placebo was very poor (<15%). There was also a pronounced discrepancy in terms of efficiency across study designs. Accounting for sample size requirements, a phase 3 program using SPCD would have a higher cumulative chance of yielding two positive trials (50%) than a phase 3 program using a single-blind placebo lead-in (40%). Future programs should carefully weigh the need for a lead-in, which is time-consuming, expensive and, in some cases (i.e., open-label antidepressant without placebo or with double-blind placebo) nearly futile. Instead, more effort should involve the use of studies where patients are directly randomized, such as the SPCD, with more investment shifted towards the accurate and independent vetting of subject eligibility.

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.

Staging Treatment Intensity and Defining Resistant Depression: Historical Overview and Future Directions.

OBJECTIVE: To review existing staging models and definitions of treatment-resistant depression (TRD) and offer future directions within the context of up-to-date evidence. DATA SOURCES: A PubMed search was conducted on February 25, 2018, for articles in English on TRD staging or definition using the following keywords: depressive disorder, treatment-resistant OR treatment resistant depression cross-referenced with staging OR degree OR level OR definition. Relevant cross-references from identified articles were also included. STUDY SELECTION: A total of 18 articles were identified that included a proposed TRD staging model, a proposed TRD definition, empirical work to support a model or definition, or any combination thereof. DATA EXTRACTION: Included articles were summarized in chronological order in terms of the date the TRD staging model (and accompanying TRD definition if applicable) was first proposed. Findings from validation studies pertaining to staging or definition were then synthesized. RESULTS: Five staging models were identified. Strengths identified across staging models include rigorous assessment of adequacy of treatment, differentiation of resistance versus symptom return, assignment of equal weights to different pharmacotherapies, and accounting for augmentation. Future considerations should include differential weighting to specific augmentation agents based on available evidence, added weight to electroconvulsive therapy and ketamine treatments, and the addition of evidence-based psychotherapies. Dichotomous versus continuous approaches to TRD diagnosis were considered, with the latter (beginning with 1 failed trial) best explaining available data from large trials. CONCLUSIONS: The most up-to-date evidence in the literature should guide future research in the definition and staging of TRD.

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.

From genes to treatments: a systematic review of the pharmacogenetics in smoking cessation.

Smoking cessation treatment outcomes may be heavily influenced by genetic variations among smokers. Therefore, identifying specific variants that affect response to different pharmacotherapies is of major interest to the field. In the current study, we systematically review all studies published in or after the year 1990 which examined one or more gene-drug interactions for smoking cessation treatment. Out of 644 citations, 46 articles met the inclusion criteria for the systematic review. We summarize evidence on several genetic polymorphisms (CHRNA5-A3-B4, CYP2A6, DBH, CHRNA4, COMT, DRD2, DRD4 and CYP2B6) and their potential moderating pharamacotherarpy effects on patient cessation efficacy rates. These findings are promising and call for further research to demonstrate the effectiveness of genetic testing in personalizing treatment decision-making and improving outcome.

A reciprocal effects analysis of cannabis use and perceptions of risk.

BACKGROUND AND AIMS: Adolescents and young adults increasingly view cannabis as a relatively safe drug. Perception of risk associated with cannabis use is correlated negatively with the prevalence of use, but the causal nature of this association is debated. The aim of this study is to quantitate the reciprocal associations between cannabis use and risk perception in a longitudinal panel of emerging adults. DESIGN: Observational study of longitudinal data from the Monitoring the Future longitudinal study using autoregressive cross-lagged panel analyses to investigate reciprocal associations between cannabis risk perception and frequency of past-year cannabis use. SETTING: Surveys administered to 12th-grade students from the United States general population. PARTICIPANTS: A total of 9929 12th-grade students (mean age 18.0 years) who were surveyed initially during 2000-05 and follow-up data until approximately 23-24 years old (three waves; n = 9929). MEASUREMENTS: Perception of risk association with cannabis use and frequency of past-year cannabis use. RESULTS: At baseline, 33% of the 12th-graders used cannabis in the past year versus 28% by the third follow-up; 83% believed that smoking cannabis regularly carried moderate or great risk versus 78% by the third follow-up. All cross-lagged paths in both directions were statistically significant (all P < 0.001), consistent with reciprocal influences between cannabis use and risk perception. The negative association between past-year cannabis use and subsequent risk perception (standardized coefficient range -0.21 to -0.27) was stronger than that between risk perception and subsequent use (standardized coefficient range -0.08 to -0.11; confidence intervals did not overlap with those for the coefficients reported above). Similar results were obtained when the analysis was limited to those who had never used cannabis prior to baseline. CONCLUSIONS: Longitudinal associations between cannabis use and perception of risks from cannabis use are reciprocal in nature, with a stronger association between cannabis use and lower subsequent risk perception.

Emergence of mania in two middle-aged patients with a history of unipolar treatment-refractory depression receiving vagus nerve stimulation.

OBJECTIVES: We report on two patients who experienced emergence of full manic symptoms while receiving vagal nerve stimulation (VNS). METHODS: Two patients, both with a well-documented and verified history of longstanding unipolar depression, were initiated on VNS for treatment of their severe major depressive episodes. RESULTS: The two patients had emergence of full manic symptoms after 8 and 9 months of VNS, respectively. Manic symptoms were adequately managed with standard treatments (mood stabilizer and electroconvulsive therapy) and VNS was continued in the two subjects for up to 5 years without any further occurrences of manic/hypomanic episodes. CONCLUSIONS: These cases suggest that some patients with treatment-resistant depression may have a previously unrecognized bipolar disorder, triggered only by VNS. This report also provides evidence that VNS-induced manic switches, however serious and troubling to patients, can be managed safely, and that VNS maintenance can be continued for an extended period of time without manic relapses. Although the mechanism of action of VNS is not known, emerging evidence supports central nervous system dopaminergic and possibly cholinergic system involvement.

Towards the clinical implementation of pharmacogenetics in bipolar disorder.

BACKGROUND: Bipolar disorder (BD) is a psychiatric illness defined by pathological alterations between the mood states of mania and depression, causing disability, imposing healthcare costs and elevating the risk of suicide. Although effective treatments for BD exist, variability in outcomes leads to a large number of treatment failures, typically followed by a trial and error process of medication switches that can take years. Pharmacogenetic testing (PGT), by tailoring drug choice to an individual, may personalize and expedite treatment so as to identify more rapidly medications well suited to individual BD patients. DISCUSSION: A number of associations have been made in BD between medication response phenotypes and specific genetic markers. However, to date clinical adoption of PGT has been limited, often citing questions that must be answered before it can be widely utilized. These include: What are the requirements of supporting evidence? How large is a clinically relevant effect? What degree of specificity and sensitivity are required? Does a given marker influence decision making and have clinical utility? In many cases, the answers to these questions remain unknown, and ultimately, the question of whether PGT is valid and useful must be determined empirically. Towards this aim, we have reviewed the literature and selected drug-genotype associations with the strongest evidence for utility in BD. SUMMARY: Based upon these findings, we propose a preliminary panel for use in PGT, and a method by which the results of a PGT panel can be integrated for clinical interpretation. Finally, we argue that based on the sufficiency of accumulated evidence, PGT implementation studies are now warranted. We propose and discuss the design for a randomized clinical trial to test the use of PGT in the treatment of BD.