A review of current evidence for vilazodone in major depressive disorder

Interactions of antidepressants with concomitant medications-safety of complex therapies in multimorbidities

Depression is the fourth most serious disease in the world. Left untreated, it is a cause of suicide attempts, emergence or exacerbation worsening of serious diseases, bodily and mental disorders, as well as increased risk of cardiovascular diseases, stroke, diabetes, and obesity, as well as endocrine and neurological diseases. Frequent coexistence of depression and other diseases requires the simultaneous use of several drugs from different therapeutic groups, which very often interact and intensify comorbidities, sometimes unrelated mechanisms. Sufficient awareness of potential drug interactions is critical in clinical practice, as it allows both to avoid disruption of proper pharmacotherapy and achieve substantive results. Therefore, this review aims to analyze the interactions of antidepressants with other concomitant medications. Against the backdrop of experimental research and a thorough analysis of the up-to-date literature, the authors discuss in detail the mechanisms and effects of action of individual drug interactions and adaptogens, including the latest antidepressants.

Indole-containing pharmaceuticals: targets, pharmacological activities, and SAR studies

Indole is a prestigious heterocyclic skeleton widely found in both naturally-occurring and biologically-active compounds. Pharmaceutical agents containing an indole skeleton in their framework possess a wide range of pharmacological properties, including antiviral, antitumor, analgesic, and other therapeutic activities, and many indole-containing drugs have been proven to have excellent pharmacokinetic and pharmacological effects. Over the past few decades, the FDA has approved over 40 indole-containing drugs for the treatment of various clinical conditions, and the development of indole-related drugs has attracted significant attention from medicinal chemists. This review aims to provide an overview of all the approved drugs that contain an indole nucleus, focusing on their targets, pharmacological activities, and SAR studies.

Utility of pharmacogenetic testing to optimise antidepressant pharmacotherapy in youth: a narrative literature review

Pharmacogenetics (PGx) is the study and application of how interindividual differences in our genomes can influence drug responses. By evaluating individuals' genetic variability in genes related to drug metabolism, PGx testing has the capabilities to individualise primary care and build a safer drug prescription model than the current "one-size-fits-all" approach. In particular, the use of PGx testing in psychiatry has shown promising evidence in improving drug efficacy as well as reducing toxicity and adverse drug reactions. Despite randomised controlled trials demonstrating an evidence base for its use, there are still numerous barriers impeding its implementation. This review paper will discuss the management of mental health conditions with PGx-guided treatment with a strong focus on youth mental illness. PGx testing in clinical practice, the concerns for its implementation in youth psychiatry, and some of the barriers inhibiting its integration in clinical healthcare will also be discussed. Overall, this paper provides a comprehensive review of the current state of knowledge and application for PGx in psychiatry and summarises the capabilities of genetic information to personalising medicine for the treatment of mental ill-health in youth.

Does human serotonin-1A receptor polymorphism (rs6295) code for pain and associated symptoms in fibromyalgia syndrome?

Genetic predisposition may play an important role in the development of fibromyalgia syndrome (FMS). Serotonin is known to be involved in pain modulation and serotonin-1A receptor plays a considerable role in determining the central 5-HT tone. Consequently, variation in 5-HT1A receptor gene (HTR1A) may be responsible for inter-individual variability in pain sensitivity and other clinical symptoms of FMS. Therefore, the objectives of this research work were to study the gene polymorphism of 5-HTR1A gene and to explore the correlation between rs6295 genotype (-1019C/G HTR1A) and duration of pain, pain intensity and pain related depression and anxiety, if any, in FMS. 5-HTR1A genotype for the C(-1019)G polymorphism was typed in 62 patients with FMS and 42 healthy subjects. Present pain intensity, components of pain and pain related depression and anxiety were assessed using the numerical pain rating scale, McGill pain questionnaire and Hamilton depression and anxiety rating scale respectively. 5-HTR1A gene was represented by three different genotypes, homozygous C/C, heterozygous C/G and homozygous G/G. Analysis of the 5-HTR1A gene showed a frequency of 58%, 31% and 11% for the C/C, C/G and G/G genotypes, respectively in FMS group. This proportion was 69%, 23% and 8% in healthy subjects. No significant correlation was observed between 5-HTR1A gene polymorphism and pain and related symptoms in FMS patients. To the best of our knowledge this is the first study which investigated the correlation between the 5-HTR1A gene polymorphism and pain intensity, the affective component of pain, pain related depression and anxiety in FMS.

Known Drugs Identified by Structure-Based Virtual Screening Are Able to Bind Sigma-1 Receptor and Increase Growth of Huntington Disease Patient-Derived Cells

Huntington disease (HD) is a devastating and presently untreatable neurodegenerative disease characterized by progressively disabling motor and mental manifestations. The sigma-1 receptor (σ1R) is a protein expressed in the central nervous system, whose 3D structure has been recently determined by X-ray crystallography and whose agonists have been shown to have neuroprotective activity in neurodegenerative diseases. To identify therapeutic agents against HD, we have implemented a drug repositioning strategy consisting of: (i) Prediction of the ability of the FDA-approved drugs publicly available through the ZINC database to interact with σ1R by virtual screening, followed by computational docking and visual examination of the 20 highest scoring drugs; and (ii) Assessment of the ability of the six drugs selected by computational analyses to directly bind purified σ1R in vitro by Surface Plasmon Resonance and improve the growth of fibroblasts obtained from HD patients, which is significantly impaired with respect to control cells. All six of the selected drugs proved able to directly bind purified σ1R in vitro and improve the growth of HD cells from both or one HD patient. These results support the validity of the drug repositioning procedure implemented herein for the identification of new therapeutic tools against HD.

QTc monitoring in adults with medical and psychiatric comorbidities: Expert consensus from the Association of Medicine and Psychiatry

OBJECTIVE

Several psychiatric medications have the potential to prolong the QTc interval and subsequently increase the risk for ventricular arrhythmias such as torsades de pointes (TdP). There is limited guidance for clinicians to balance the risks and benefits of treatments.

METHODS

After a review of the existing literature, clinical-educators from the Association of Medicine and Psychiatry developed expert consensus guidelines for ECG monitoring of the QTc interval for patients with medical and psychiatric comorbidities who are prescribed medications with the potential to prolong the QTc interval. A risk score was developed based on risk factors for QTc prolongation to guide clinical decision-making.

RESULTS

A baseline ECG may not be necessary for individuals at low risk for arrythmia. Those individuals with a risk score of two or more should have an ECG prior to the start of a potentially QTc-prolonging medication or be started on a lower risk agent. Antipsychotics are not equivalent in causing QTc prolongation. A consensus-based algorithm is presented for the management of those identified at high (QTc >500 msec), intermediate (males with QTc 450-499 msec or females with QTc > 470-499 msec), or low risk.

CONCLUSIONS

The proposed algorithm can help clinicians in determining whether ECG monitoring should be considered for a given patient. These guidelines preserve a role for clinical judgment in selection of treatments that balance the risks and benefits, which may be particularly relevant for complex patients with medical and psychiatric comorbidities. Additional studies are needed to determine whether baseline and serial ECG monitoring reduces mortality.

Accidental intoxications in toddlers: lack of cross-reactivity of vilazodone and its urinary metabolite M17 with drug of abuse screening immunoassays

Background

Vilazodone is an FDA approved medication used to treat major depressive disorder. The authors describe two cases of accidental vilazodone exposure in toddlers who presented with symptoms similar to amphetamine exposure and also with unexplained positive amphetamine urine immunoassay drug screens. Given a lack of published data on cross-reactivity of vilazodone and its metabolites with drug of abuse screening tests, the authors investigated drug of abuse immunoassay cross-reactivity of vilazodone and metabolites using computational and empirical approaches.

Methods

To ascertain the likelihood that vilazodone would cross-react with drug of abuse screening immunoassays, the authors assessed the two-dimensional (2D) similarity of the vilazodone parent molecule and known metabolites to an array of antigenic targets for urine immunoassay drug screens. To facilitate studies of the commercially unavailable M17 metabolite, it was prepared synthetically through a novel scheme. Urine and serum were spiked with vilazodone and M17 into urine (200–100,000 ng/mL) and serum (20–2000 ng/mL) samples and tested for cross-reactivity.

Results

Computational analysis using 2D similarity showed that vilazodone and metabolites have generally low similarity to antigenic targets of common drug of abuse screening immunoassays, predicting weak or no cross-reactivity. The M17 metabolite had 2D similarity to amphetamines and tricyclic antidepressants in a range similar to some other compounds exhibiting weak cross-reactivity on these immunoassays. Cross-reactivity testing was therefore performed on two different urine amphetamines immunoassays and a serum tricyclic antidepressant immunoassay. However, actual testing of cross reactivity for vilazodone and the M17 metabolite did not detect cross-reactivity for any urine amphetamines screen at concentrations up to 100,000 ng/mL and for a serum tricyclic antidepressants assays at concentrations up to 2000 ng/mL.

Conclusion

While the vilazodone metabolite M17 has weak 2D structural similarity to amphetamines and tricyclic antidepressants, the current study did not demonstrate any experimental cross-reactivity with two different urine amphetamines immunoassays and a serum tricyclic antidepressant immunoassay. Vilazodone ingestions in young children present a diagnostic challenge in their similarity to amphetamine ingestions and the lack of routine laboratory tests for vilazodone. Further work is needed to understand the metabolic profile for vilazodone in children versus adults.

Electronic supplementary material

The online version of this article (10.1186/s12907-019-0084-9) contains supplementary material, which is available to authorized users.

Adverse effects and treatment satisfaction among online users of four antidepressants

Adverse effects (AEs) are an important factor in antidepressant treatment decision-making, though common AE profiles from clinical trial research highlight physical AEs to the neglect of emotional and behavioral AEs. First-hand accounts of antidepressant users on the Internet can supplement AE profiles with information gained from real-world treatment experiences. We examined online user reviews of two older (escitalopram; duloxetine) and two newer (vilazodone; vortioxetine) antidepressants for differences in their AE profiles and determined which categories of AEs were associated with users' satisfaction. A codebook of 60 physical, emotional, and behavioral AEs was used for line-by-line coding of effects reported among 3243 user reviews from three popular health websites. Emotional and behavioral effects were commonly reported (41%), followed by sleep (31.9%) and gastrointestinal (25.0%) effects. Specific AEs statistically significantly varied across drugs, creating potentially meaningful differences in AE profiles. Users of newer drugs more often reported emotional instability, while users of older drugs reported more emotional blunting. Emotional and behavioral AEs demonstrated moderate to substantial relationships with users' satisfaction, whereas gastrointestinal, metabolic, or sexual AEs were minimally related. More specific and systematic assessment of a broader range of AEs is needed in both research and practice.

Canadian Network for Mood and Anxiety Treatments (CANMAT) 2016 Clinical Guidelines for the Management of Adults with Major Depressive Disorder: Section 3. Pharmacological Treatments

BACKGROUND

The Canadian Network for Mood and Anxiety Treatments (CANMAT) conducted a revision of the 2009 guidelines by updating the evidence and recommendations. The scope of the 2016 guidelines remains the management of major depressive disorder (MDD) in adults, with a target audience of psychiatrists and other mental health professionals.

METHODS

Using the question-answer format, we conducted a systematic literature search focusing on systematic reviews and meta-analyses. Evidence was graded using CANMAT-defined criteria for level of evidence. Recommendations for lines of treatment were based on the quality of evidence and clinical expert consensus. "Pharmacological Treatments" is the third of six sections of the 2016 guidelines. With little new information on older medications, treatment recommendations focus on second-generation antidepressants.

RESULTS

Evidence-informed responses are given for 21 questions under 4 broad categories: 1) principles of pharmacological management, including individualized assessment of patient and medication factors for antidepressant selection, regular and frequent monitoring, and assessing clinical and functional outcomes with measurement-based care; 2) comparative aspects of antidepressant medications based on efficacy, tolerability, and safety, including summaries of newly approved drugs since 2009; 3) practical approaches to pharmacological management, including drug-drug interactions and maintenance recommendations; and 4) managing inadequate response and treatment resistance, with a focus on switching antidepressants, applying adjunctive treatments, and new and emerging agents.

CONCLUSIONS

Evidence-based pharmacological treatments are available for first-line treatment of MDD and for management of inadequate response. However, given the limitations of the evidence base, pharmacological management of MDD still depends on tailoring treatments to the patient.

Comparative efficacy of selective serotonin reuptake inhibitors (SSRI) in treating major depressive disorder: a protocol for network meta-analysis of randomised controlled trials

INTRODUCTION

There have been inconsistent findings from randomised controlled trials (RCTs) and systematic reviews on the efficacies of selective serotonin reuptake inhibitors (SSRIs) as the first-line treatment of major depressive disorder (MDD). Besides inconsistencies among randomised controlled trials (RCTs), their risks of bias and evidence grading have seldom been evaluated in meta-analysis. This study aims to compare the efficacy of SSRIs by conducting a Bayesian network meta-analysis, which will be the most comprehensive evaluation of evidence to resolve the inconsistency among previous studies.

METHODS AND ANALYSES

SSRIs including citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, sertraline and vilazodone have been selected. Systematic database searching and screening will be conducted for the RCTs on drug treatment of patients with MDD according to pre-specified search strategies and selection criteria. PubMed, the Cochrane Library, EMBASE, ScienceDirect, the US Food and Drug Administration Website, ClinicalTrial.gov and WHO Clinical Trials will be searched. Outcome data including Hamilton Depression Rating Scale (HDRS), Montgomery-Åsberg Depression Rating Scale (MADRS) and Clinical Global Impression (CGI) from eligible RCTs will be extracted. The outcomes will be analysed as ORs and mean differences under a random-effects model. A Bayesian network meta-analysis will be conducted with WinBUGS software, to compare the efficacies of SSRIs. Subgroup and sensitivity analysis will be performed to explain the study heterogeneity and evaluate the robustness of the results. Meta-regression analysis will be conducted to determine the possible factors affecting the efficacy outcomes. The Cochrane risk of bias assessment tool will be used to assess the RCT quality, and the Grading of Recommendation, Assessment, Development and Evaluation will be used to assess the strength of evidence from the meta-analysis.

ETHICS AND DISSEMINATION

No ethical approval is required because this study includes neither confidential personal patient data nor interventions with patients.

PROTOCOL REGISTRATION NUMBER

CRD42015024879.

Vilazodone for the Treatment of Depression: An Update

Vilazodone is a novel antidepressant having a selective serotonin (5-HT) reuptake inhibitor and 5-HT1A receptor partial agonist profile, so it has been regarded as a serotonin partial agonist-reuptake inhibitor (SPARI). We aimed to provide Vilazodone's clinical implications mainly by reviewing published clinical trials. Vilazodone has been speculated to have three potential benefits including faster onset of action, greater efficacy, and better tolerability owning to its SPARI properties. However, no studies conducted so far have directly proven the above speculations. Five initial phase II trials failed to distinguish vilazodone from placebo in the treatment of MDD, but 4 randomized clinical trials (RCT), 3 post-hoc or pooled analysis, 1 long-term open label study, and a meta-analysis showed vilazodone's superior efficacy over placebo. The studies also showed vilazodone is generally safe and tolerable. However, diarrhea, nausea, headache, dizziness, dry mouth, and insomnia warrant close attention in clinical practice because they have been constantly noted throughout the clinical studies. 2 RCTs recently documented the efficacy and safety of vilazodone in patients with generalized anxiety disorder, which could be a start of broadening vilazodone's usage or FDA approval in diverse anxiety disorders.

The functional serotonin 1a receptor promoter polymorphism, rs6295, is associated with psychiatric illness and differences in transcription

The G/C single-nucleotide polymorphism in the serotonin 1a receptor promoter, rs6295, has previously been linked with depression, suicide and antidepressant responsiveness. In vitro studies suggest that rs6295 may have functional effects on the expression of the serotonin 1a receptor gene (HTR1A) through altered binding of a number of transcription factors. To further explore the relationship between rs6295, mental illness and gene expression, we performed dual epidemiological and biological studies. First, we genotyped a cohort of 1412 individuals, randomly split into discovery and replication cohorts, to examine the relationship between rs6295 and five psychiatric outcomes: history of psychiatric hospitalization, history of suicide attempts, history of substance or alcohol abuse, current posttraumatic stress disorder (PTSD), current depression. We found that the rs6295G allele is associated with increased risk for substance abuse, psychiatric hospitalization and suicide attempts. Overall, exposure to either childhood or non-childhood trauma resulted in increased risk for all psychiatric outcomes, but we did not observe a significant interaction between rs6295 and trauma in modulating psychiatric outcomes. In conjunction, we also investigated the potential impact of rs6295 on HTR1A expression in postmortem human brain tissue using relative allelic expression assays. We found more mRNA produced from the C versus the G-allele of rs6295 in the prefrontal cortex (PFC), but not in the midbrain of nonpsychiatric control subjects. Further, in the fetal cortex, rs6295C allele exhibited increased relative expression as early as gestational week 18 in humans. Finally, we found that the C:G allelic expression ratio was significantly neutralized in the PFC of subjects with major depressive disorder (MDD) who committed suicide as compared with controls, indicating that normal patterns of transcription may be disrupted in MDD/suicide. These data provide a putative biological mechanism underlying the association between rs6295, trauma and mental illness. Moreover, our results suggest that rs6295 may affect transcription during both gestational development and adulthood in a region-specific manner, acting as a risk factor for psychiatric illness. These findings provide a critical framework for conceptualizing the effects of a common functional genetic variant, trauma exposure and their impact on mental health.

Optimizing the Use of Aripiprazole Augmentation in the Treatment of Major Depressive Disorder: From Clinical Trials to Clinical Practice

Major depressive disorder (MDD) is a recurrent, chronic, and devastating disorder leading to serious impairment in functional capacity as well as increasing public health care costs. In the previous decade, switching therapy and dose adjustment of ongoing antidepressants was the most frequently chosen subsequent treatment option for MDD. However, such recommendations were not based on firmly proven efficacy data from well-designed, placebo-controlled, randomized clinical trials (RCTs) but on practical grounds and clinical reasoning. Aripiprazole augmentation has been dramatically increasing in clinical practice owing to its unique action mechanisms as well as proven efficacy and safety from adequately powered and well-controlled RCTs. Despite the increased use of aripiprazole in depression, limited clinical information and knowledge interfere with proper and efficient use of aripiprazole augmentation for MDD. The objective of the present review was to enhance clinicians' current understanding of aripiprazole augmentation and how to optimize the use of this therapy in the treatment of MDD.

Vilazodone for the treatment of major depressive disorder: focusing on its clinical studies and mechanism of action

We tried to review and update clinical and preclinical studies evaluating vilazodone's role as an antidepressant for patients with major depressive disorder (MDD). In terms of its mechanism of actions, we sought to elaborate them mainly through preclinical animal studies. A data search was conducted in November 1, 2013, using the key terms "vilazodone" or "Viibryd," in PubMed and Medline databases. All published and unpublished studies are included and citations from publications were also reviewed for additional references. Five unpublished, phase-II and two pivotal published phase-III clinical trials with nearly identical design (8-week, double-blind, randomized, and placebo-controlled) investigated efficacy of vilazodone, were found for the treatment of patients with MDD. Two post-hoc studies and one long-term open study were also included. Data were thoroughly reviewed to incorporate the pharmacology, action mechanism, efficacy and safety for the vilazodone in the treatment of major depressive disorder. Vilazodone is an antidepressant with novel mechanism of action because its chemical structure is unrelated to conventional antidepressant, and it has a selective serotonin (5-HT) reuptake inhibitor and 5-HT1A receptor partial agonist profile. Vilazodone is an effective and safe treatment option with its novel action mechanisms for patients with depression. Its putative benefits compared with other antidepressants must be thoroughly studied in adequately-powered and well-designed future clinical trials.

Health resource use and costs of vilazodone and other selective serotonin re-uptake inhibitors in treating major depressive disorder

OBJECTIVE

Selective serotonin re-uptake inhibitors (SSRIs) are widely prescribed antidepressants. This claims database study compared healthcare resource use and costs among patients with major depressive disorder (MDD) treated with vilazodone vs other SSRIs.

METHODS

Adults with an MDD diagnosis and ≥ 1 prescription fill for vilazodone, citalopram, escitalopram, fluoxetine, paroxetine, or sertraline were identified from administrative claims data (2010-2012). Patients who concomitantly used adjunctive medication, either a second-generation antidepressant or antipsychotic, were excluded. All-cause and MDD-related healthcare resource use and costs (in 2012 USD) were compared between patients treated with vilazodone vs other SSRIs over a 6-month follow-up period using unadjusted and multivariable analyses.

RESULTS

The study cohort included 49 861 patients (mean age = 44.0 years; 70% female). Compared with the vilazodone cohort (n = 3527), patients in the citalopram (n = 12 187), escitalopram (n = 8275), fluoxetine (n = 10 142), paroxetine (n = 3146), and sertraline (n = 12 584) cohorts had significantly more all-cause inpatient hospital visits, longer hospital stays and more frequent emergency department visits, following the index date, after adjusting for baseline characteristics. All-cause medical service costs (inpatient + outpatient + emergency department visits) were significantly higher across all other SSRI cohorts vs vilazodone by $758-$1165 (p < 0.05). Similarly, all-cause total costs, were significantly or numerically (non-significantly) higher across all SSRI cohorts vs vilazodone by $351-$780.

LIMITATIONS

The was no clinical measurement of disease severity, partial coverage of the Medicare-eligible population, and short follow-up.

CONCLUSION

MDD treatment with vilazodone was associated with significantly lower rates of inpatient and emergency services, and with significantly lower all-cause medical service costs and numerically (non-significantly) lower total costs to payers than with the other SSRIs included in this study.

Evaluation of the efficacy and safety of vilazodone for treating major depressive disorder

PURPOSE

Vilazodone is a novel serotonin (5-HT)-reuptake inhibitor and 5-HT1A partial agonist that was recently developed for the treatment of major depressive disorder (MDD). We conducted a meta-analysis and systematic review to better evaluate the efficacy and safety of vilazodone.

MATERIALS AND METHODS

We performed a thorough literature search to identify all randomized double-blind placebo-controlled trials that were designed to investigate the efficacy of vilazodone for the treatment of MDD, and that were published in electronic databases, including Medline, Embase, and the Cochrane Central Register of Controlled Trials. A manual search was also conducted to investigate the relevant references of the retrieved studies. Subsequently, we conducted a meta-analysis and systematic literature review.

RESULTS

A total of five randomized controlled trials were finally included, involving 1,200 patients with vilazodone and 1,193 patients with placebo. The primary efficacy end point of the Montgomery-Åsberg Depression Rating Scale (standardized mean difference -3.58, 95% confidence interval -4.59 to -2.56; P<0.00001), and the key secondary efficacy end points (Clinical Global Impression - Severity scale, Clinical Global Impression - Improvement scale, and Hamilton Anxiety Rating Scale) indicated that vilazodone was more effective than placebo. Most common adverse events, including diarrhea and nausea, were evaluated, and safety assessments indicated that vilazodone was well tolerated (diarrhea odds ratio 3.54, 95% confidence interval 2.81-4.45; P<0.00001; nausea odds ratio 3.85, 95% confidence interval 3.00-4.96; P<0.00001; discontinuations due to adverse events odds ratio 2.71, 95% confidence interval 1.81-4.05; P<0.00001).

CONCLUSION

Our findings indicate that the novel antidepressant vilazodone is effective and safe for MDD, with a low occurrence of side effects. It offers promise as an effective oral drug for the treatment of MDD, with a balance of efficacy and tolerability.

Risk of QT/QTc Prolongation Among Newer Non-SSRI Antidepressants

Objective: To review QT prolongation potential with newer nonselective serotonin reuptake inhibitor (non-SSRI) antidepressants. Data Sources: A PubMed literature search was performed from 1982 through June 16, 2014. Search terms included bupropion, desvenlafaxine, duloxetine, levomilnacipran, mirtazapine, venlafaxine, and vilazodone in combination with each of the following terms: cardiac toxicity, QTc prolongation, QT prolongation, torsades de pointes, and TdP. Study Selection and Data Extraction: English-language human studies, case reports, package inserts, manufacturer electronic communications, and ArizonaCert database were utilized. Data Synthesis: Rare QT prolongation has been reported with venlafaxine at therapeutic doses and in overdose. Bupropion has also been linked to QT prolongation in overdose situations. In elderly patients with a variety of high-risk comorbidities, mirtazapine did demonstrate higher odds of sudden cardiac death and ventricular arrhythmias when compared with paroxetine. Largely because of a lack of available data, existing studies fail to demonstrate QT prolongation with desvenlafaxine, duloxetine, levomilnacipran, and vilazodone. Conclusion: Based on the current literature, risk of QT/QTc prolongation with the majority of newer non-SSRI antidepressants at therapeutic doses is low. The highest risk for QT prolongation appears to exist in overdose situations with venlafaxine and bupropion. Given the few to nonexistent controlled studies and confounding variables present in case reports, it is difficult to draw conclusions on QT prolongation risk with many of the newer non-SSRI antidepressants.

Serotonergic modulation of glutamate neurotransmission as a strategy for treating depression and cognitive dysfunction

Monoamine-based treatments for depression have evolved greatly over the past several years, but shortcomings such as suboptimal efficacy, treatment lag, and residual cognitive dysfunction are still significant. Preclinical and clinical studies using compounds directly targeting glutamatergic neurotransmission present new opportunities for antidepressant treatment, with ketamine having a surprisingly rapid and sustained antidepressant effect that is presumably mediated through glutamate-dependent mechanisms. While direct modulation of glutamate transmission for antidepressant and cognition-enhancing actions may be hampered by nonspecific effects, indirect modulation through the serotonin (5-HT) system may be a viable alternative approach. Based on localization and function, 5-HT can modulate glutamate neurotransmission at least through the 5-HT1A, 5-HT1B, 5-HT3, and 5-HT7 receptors, which presents a rational pharmacological opportunity for modulating glutamatergic transmission without the direct use of glutamatergic compounds. Combining one or more of these glutamate-modulating 5-HT targets with 5-HT transporter inhibition may offer new therapeutic opportunities. The multimodal compounds vortioxetine and vilazodone are examples of this approach with diverse mechanisms, and their different clinical effects will provide valuable insights into serotonergic modulation of glutamate transmission for the potential treatment of depression and associated cognitive dysfunction.