Efficacy of agomelatine, a MT1/MT2 receptor agonist with 5-HT2C antagonistic properties, in major depressive disorder

Agomelatine alleviates steroid-induced osteoporosis by targeting SIRT1/RANKL/FOXO1/OPG signalling in rats

One of the major contributors to secondary osteoporosis is long-term glucocorticoid usage. Clinically used antidepressant agomelatine also has anti-inflammatory properties. Our research aimed to inspect the probable defensive effect of agomelatine against steroid-promoted osteoporosis. There were four groups of rats; group I had saline as a negative control; rats of group II had dexamethasone (0.6 mg/kg, s.c.), twice weekly for 12 weeks; rats of group III had agomelatine (40 mg/kg/day, orally), as a positive control, daily for 12 weeks; and rats of group IV had dexamethasone + agomelatine in the same previous doses combined for 12 weeks. Finally, biochemical as well as histopathological changes were evaluated and dexamethasone treatment caused osteoporosis, as evidenced by discontinuous thin cancellous bone trabeculae, minor fissures and fractures, irregular eroded endosteal surface with elevated alkaline phosphate, tartarate resistant acid phosphate (TRACP) and osteocalcin levels. Osteoprotegerin (OPG), calcium, and phosphorus levels decreased with disturbed receptor activator of nuclear factor κ B ligand (RANKL), forkhead box O1 (FOXO1), and silent information regulator 1 (SIRT1) protein expression. However, treatment with agomelatine restored the normal levels of biochemical parameters to a great extent, supported by SIRT activation with an improvement in histopathological changes. Here, we concluded that agomelatine ameliorates steroid-induced osteoporosis through a SIRT1/RANKL/FOXO1/OPG-dependent pathway.

Efficacy and safety of agomelatine in the treatment of patients with depressive disorder: A meta-analysis

OBJECTIVE

To systematically assess the efficacy and safety of agomelatine in the treatment of patients with depressive disorder.

METHODS

Randomized controlled trials (RCTs) related to agomelatine in the treatment of patients with depressive disorder published in PubMed, Web of Science, CNKI, VIP, and Wangfang were retrieved. Extracted data on the efficacy and safety of agomelatine and placebo in the treatment of depressive disorder, and the collected data were processed by RevMan5.4 software.

RESULTS

A total of 10 RCTs were included. Meta-analysis showed that the HAMD-17 total scores of agomelatine group were statistically different from those of placebo group (odds ratio [OR]: 2.04, 95% confidence intervals [CIs]: 1.71-2.43, P < .001). High heterogeneity was found between agomelatine groups and placebo groups (P < .0001, and I2 = 78%), so a subgroup analysis was further performed, and the heterogeneity became insignificant (P = .33, and I2 = 14%) after excluding the studies, of which course of treatment was 24 weeks or the sample size was relatively small. The adverse events between agomelatine and placebo groups were not statistically significant (OR: 1.15, 95% CIs: 0.69-1.92; P = .05).

CONCLUSION

Agomelatine was superior comparable to placebo in the treatment of patients with depressive disorder, and has fewer adverse events.

Latest updates on the serotonergic system in depression and anxiety

Psychiatric disorders are among the leading causes of global health burden, with depression and anxiety being the most disabling subtypes. The two common disorders, depression and anxiety, usually coexist and are pathologically polygenic with complicated etiologies. Current drug-based therapies include selective serotonin reuptake inhibitors, serotonin and norepinephrine reuptake inhibitors, and 5-hydroxytryptamine partial agonists. However, these modalities share common limitations, such as slow onset and low efficacy, which is why potential mechanistic insights for new drug targets are needed. In this review, we summarize recent advances in brain localization, pathology, and therapeutic mechanisms of the serotonergic system in depression and anxiety.

Antidepressant efficacy of Agomelatine: Meta-analysis of placebo controlled and active comparator studies

Agomelatine is a novel antidepressant that was developed to counter the adverse effects associated with the standard SSRIs and SNRIs that limited their usage. Publication bias was identified in antidepressant trials which can potentially overestimate the treatment efficacy. This meta-analysis was designed to assess the overall antidepressant effect of Agomelatine by pooling all the published and unpublished studies available till date. Studies conducted on adult patients who met with the criteria for MDD that evaluated efficacy of Agomelatine at acute phase (6-12weeks) and at long term phase (24weeks) were included. The primary efficacy measured with SMD of final mean scores of HAM-D and MADRS. Secondary efficacy measures of Response, remission and safety parameters were evaluated with relative risks. RevMan version 5.4 was used for analysis of both continuous (Standardized mean difference) and dichotomous outcomes (response, remission and all cause of discontinuation). Efficacy parameters were presented with 99% confidence intervals while safety parameters were presented with 95% CI. A total of 9233 patients were included from 27 studies. In acute phase placebo controlled studies, Agomelatine had a statistically significant SMD of - 0.24 (-0.39 to -0.09) and response rate of (1.25, 1.07-1.47). In comparison (RR 0.99, 0.92-1.07) Agomelatine is an effective antidepressant having similar efficacy with the currently used antidepressants.

Patient fibroblast circadian rhythms predict lithium sensitivity in bipolar disorder

Bipolar disorder is a chronic neuropsychiatric condition associated with mood instability, where patients present significant sleep and circadian rhythm abnormalities. Currently, the pathophysiology of bipolar disorder remains elusive, but treatment with lithium continues as the benchmark pharmacotherapy, functioning as a potent mood stabilizer in most, but not all patients. Lithium is well documented to induce period lengthening and amplitude enhancement of the circadian clock. Based on this, we sought to investigate whether lithium differentially impacts circadian rhythms in bipolar patient cell lines and crucially if lithium's effect on the clock is fundamental to its mood-stabilizing effects. We analyzed the circadian rhythms of bipolar patient-derived fibroblasts (n = 39) and their responses to lithium and three further chronomodulators. Here we show, relative to controls (n = 23), patients exhibited a wider distribution of circadian period (p < 0.05), and that patients with longer periods were medicated with a wider range of drugs, suggesting lower effectiveness of lithium. In agreement, patient fibroblasts with longer periods displayed muted circadian responses to lithium as well as to other chronomodulators that phenocopy lithium. These results show that lithium differentially impacts the circadian system in a patient-specific manner and its effect is dependent on the patient's circadian phenotype. We also found that lithium-induced behavioral changes in mice were phenocopied by modulation of the circadian system with drugs that target the clock, and that a dysfunctional clock ablates this response. Thus, chronomodulatory compounds offer a promising route to a novel treatment paradigm. These findings, upon larger-scale validation, could facilitate the implementation of a personalized approach for mood stabilization.

The association between placebo arm inclusion and adverse event rates in antidepressant randomized controlled trials: An examination of the Nocebo Effect

BACKGROUND

Antidepressant efficacy is influenced by patient expectations and, in randomized controlled trials (RCTs), the probability of receiving a placebo. It is unclear whether tolerability demonstrates a similar pattern. This study aimed to determine whether study design influences adverse event (AE) rates in antidepressant trials for subjects receiving active treatment or placebo.

METHODS

RCTs comparing one antidepressant to another antidepressant, placebo, or both in major depressive disorder (MDD) (1996-2018) were retrieved from Medline and PsycINFO. Clinicaltrials.gov was searched for unpublished trials. Of 1,997 studies screened, 77 trials were included. Studies were classified as drug-drug, drug-drug-placebo, or drug-placebo based on design and overall number of subjects experiencing any AE was recorded. Subgroup meta-analysis of proportions and meta-regression techniques were used to compare AE rates across study designs in patients receiving active antidepressant treatment and placebo.

RESULTS

Among the actively treated, AE rates were lower in drug-drug trials (58.5%) compared to drug-drug-placebo (75.7%) and drug-placebo (76.4%) (the model reported coefficients for percent differences between AE rates of different study designs were B=17.0, p<0.001 and B=17.8, p<0.001, respectively). AE rates in patients receiving placebo were not different between study designs.

LIMITATIONS

The present study is limited by the diverse range of study populations, variability in reporting of AEs, and specific antidepressants employed in the included trials.

CONCLUSIONS

The inclusion of a placebo arm in the study design was unexpectedly associated with higher rates of AEs among patients receiving active medication in antidepressant trials. This observation has important implications for interpretation of trial tolerability findings.

Individual Differences in Response to Antidepressants: A Meta-analysis of Placebo-Controlled Randomized Clinical Trials

IMPORTANCE

Antidepressants are commonly used worldwide to treat major depressive disorder. Symptomatic response to antidepressants can vary depending on differences between individuals; however, this variability may reflect nonspecific or random factors.

OBJECTIVES

To investigate the assumption of systematic variability in symptomatic response to antidepressants and to assess whether this variability is associated with severity of major depressive disorder, antidepressant class, or year of study publication.

DATA SOURCES

Data used were from a recent network meta-analysis of acute treatment with licensed antidepressants in adults with major depressive disorder. The following databases were searched from inception to January 8, 2016: the Cochrane Central Register of Controlled Trials, CINAHL, Embase, LILACS database, MEDLINE, MEDLINE In-Process, and PsycINFO. Additional sources were international trial registries, drug approval agency websites, and key scientific journals.

STUDY SELECTION

Analysis was restricted to double-blind, randomized placebo-controlled trials with available data at the study's end point.

DATA EXTRACTION AND SYNTHESIS

Baseline and end point means, SDs, number of participants in each group, antidepressant class, and publication year were extracted. The data were analyzed between August 14 and November 18, 2019.

MAIN OUTCOMES AND MEASURES

With the use of validated methods, coefficients of variation were derived for antidepressants and placebo, and their ratios were calculated to compare outcome variability between antidepressant and placebo. Ratios were entered into a random-effects model, with the expectation that response to antidepressants would be more variable than response to placebo. Analysis was repeated after stratifying by baseline severity of depression, antidepressant class (selective serotonin reuptake inhibitors: citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, and vilazodone; serotonin and norepinephrine reuptake inhibitors: desvenlafaxine and venlafaxine; norepinephrine-dopamine reuptake inhibitor: bupropion; noradrenergic agents: amitriptyline and reboxetine; and other antidepressants: agomelatine, mirtazapine, and trazodone), and publication year.

RESULTS

In the 87 eligible randomized placebo-controlled trials (17 540 unique participants), there was significantly more variability in response to antidepressants than to placebo (coefficients of variation ratio, 1.14; 95% CI, 1.11-1.17; P < .001). Baseline severity of depression did not moderate variability in response to antidepressants. Variability in response to selective serotonin reuptake inhibitors was lower than variability in response to noradrenergic agents (coefficients of variation ratio, 0.88; 95% CI, 0.80-0.97; P = .01), as was the variability in response to other antidepressants compared with noradrenergic agents (coefficients of variation ratio, 0.87; 95% CI, 0.79-0.97; P = .001). Variability also tended to be lower in studies that were published more recently, with coefficients of variation changing by a value of 0.005 (95% CI, 0.002-0.008; P = .003) for every year a study is more recent.

CONCLUSIONS AND RELEVANCE

Individual differences may be systematically associated with responses to antidepressants in major depressive disorder beyond placebo effects or statistical factors. This study provides empirical support for identifying moderators and personalizing antidepressant treatment.

Application of Item Response Theory to Model Disease Progression and Agomelatine Effect in Patients with Major Depressive Disorder

INTRODUCTION

In this paper, we studied the effect over time of agomelatine, an antidepressant drug administered in patient with major depressive disorder, through item response theory (IRT), taking into account a strong placebo effect and missing not at random. We also assessed the informativeness of the HAMD-17 scale's item.

MATERIALS AND METHODS

The data includes five phase III clinical trials sponsored by Servier Institute, totalling 1549 patients followed during a maximum of 1 year. At each observation, individual scores for the 17 items of the HAMD scale were recorded. The probability for each score was modelled with IRT. A non-linear mixed effects model was used to describe the evolution of the disease and was coupled with a time to event model to predict dropout. Clinical trial simulations were then used to compare placebo and active treatment. Informativeness of each item was evaluated using the Fisher information theory.

RESULTS

The best model combined an IRT model, a longitudinal model for underlying depression which describes the remission and then a possible relapse, and a hazard model for dropout depending on the evolution from baseline. The drug effect was best modelled as an effect on the remission and the relapse phases. The median predicted drop in HAMD between baseline and 6 weeks was 8.8 (90% PI, 8.3-9.2) when on placebo and 13.1 (90% PI, 12.8-13.4) when treated. Nine items were found to be the most informative.

CONCLUSION

The IRT framework allowed to characterise the evolution of depression with time and estimate the effect of agomelatine, as well as the link between symptoms and disease.

Anxiolytic properties of compounds that counteract oxidative stress, neuroinflammation, and glutamatergic dysfunction: a review

Objective:

Anxiety disorders are highly prevalent and the efficacy of the available anxiolytic drugs is less than desired. Adverse effects also compromise patient quality of life and adherence to treatment. Accumulating evidence shows that the pathophysiology of anxiety and related disorders is multifactorial, involving oxidative stress, neuroinflammation, and glutamatergic dysfunction. The aim of this review was to evaluate data from animal studies and clinical trials showing the anxiolytic effects of agents whose mechanisms of action target these multiple domains.

Methods:

The PubMed database was searched for multitarget agents that had been evaluated in animal models of anxiety, as well as randomized double-blind placebo-controlled clinical trials of anxiety and/or anxiety related disorders.

Results:

The main multitarget agents that have shown consistent anxiolytic effects in various animal models of anxiety, as well in clinical trials, are agomelatine, N-acetylcysteine (NAC), and omega-3 fatty acids. Data from clinical trials are preliminary at best, but reveal good safety profiles and tolerance to adverse effects.

Conclusion:

Agomelatine, NAC and omega-3 fatty acids show beneficial effects in clinical conditions where mainstream treatments are ineffective. These three multitarget agents are considered promising candidates for innovative, effective, and better-tolerated anxiolytics.

Advances of Melatonin-Based Therapies in the Treatment of Disturbed Sleep and Mood

Melatonin and melatonin agonists offer novel treatments for sleep and mood disorders, particularly where circadian misalignment is also present. The therapies offer both phase-shifting and sleep-promoting effects and have shown potential to treat advanced and delayed sleep-wake phase disorder, non-24-h sleep-wake cycle, jetlag, shift work disorder, insomnia, seasonal affective disorder and major depressive disorder.

Molecular basis of atypicality of bupropion inferred from its receptor engagement in nervous system tissues

Despite decades of clinical use and research, the mechanism of action (MOA) of antidepressant medications remains poorly understood. Selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) are the most commonly prescribed antidepressants-atypical antidepressants such as bupropion have also proven effective, while exhibiting a divergent clinical phenotype. The difference in phenotypic profiles presumably lies in the differences among the MOAs of SSRIs/SNRIs and bupropion. We integrated the ensemble of bupropion's affinities for all its receptors with the expression levels of those targets in nervous system tissues. This "combined target tissue" profile of bupropion was compared to those of duloxetine, fluoxetine, and venlafaxine to isolate the unique target tissue effects of bupropion. Our results suggest that the three monoamines-serotonin, norepinephrine, and dopamine-all contribute to the common antidepressant effects of SSRIs, SNRIs, and bupropion. At the same time, bupropion is unique in its action on 5-HT3AR in the dorsal root ganglion and nicotinic acetylcholine receptors in the pineal gland. These unique tissue-specific activities may explain unique therapeutic effects of bupropion, such as pain management and smoking cessation, and, given melatonin's association with nicotinic acetylcholine receptors and depression, highlight the underappreciated role of the melatonergic system in bupropion's MOA.

The role of 5-HT receptors in depression

Depression is a polygenic and highly complex psychiatric disorder that remains a major burden on society. Antidepressants, such as selective serotonin reuptake inhibitors (SSRIs), are some of the most commonly prescribed drugs worldwide. In this review, we will discuss the evidence that links serotonin and serotonin receptors to the etiology of depression and the mechanisms underlying response to antidepressant treatment. We will then revisit the role of serotonin in three distinct hypotheses that have been proposed over the last several decades to explain the pathophysiology of depression: the monoamine, neurotrophic, and neurogenic hypotheses. Finally, we will discuss how recent studies into serotonin receptors have implicated specific neural circuitry in mediating the antidepressant response, with a focus being placed on the hippocampus.

Clock-Enhancing Small Molecules and Potential Applications in Chronic Diseases and Aging

Normal physiological functions require a robust biological timer called the circadian clock. When clocks are dysregulated, misaligned, or dampened, pathological consequences ensue, leading to chronic diseases and accelerated aging. An emerging research area is the development of clock-targeting compounds that may serve as drug candidates to correct dysregulated rhythms and hence mitigate disease symptoms and age-related decline. In this review, we first present a concise view of the circadian oscillator, physiological networks, and regulatory mechanisms of circadian amplitude. Given a close association of circadian amplitude dampening and disease progression, clock-enhancing small molecules (CEMs) are of particular interest as candidate chronotherapeutics. A recent proof-of-principle study illustrated that the natural polymethoxylated flavonoid nobiletin directly targets the circadian oscillator and elicits robust metabolic improvements in mice. We describe mood disorders and aging as potential therapeutic targets of CEMs. Future studies of CEMs will shed important insight into the regulation and disease relevance of circadian clocks.

Insomnia in Adults With Chronic Hepatitis B, Liver Failure, and Cirrhosis: A Case-Control Study

PURPOSE

To determine the frequency and socio-demographic/clinical correlates of insomnia in patients with chronic hepatitis B, hepatitis B virus (HBV)-related liver failure, and cirrhosis.

DESIGN AND METHODS

Up to 120 patients with HBV-related diseases and 40 matched healthy controls were recruited. Depressive and anxiety symptoms, early, middle, and late insomnia were measured.

FINDINGS

The frequency of ≥1 type of insomnia was 64.2% in patients and 35.0% in controls; frequencies of early, middle, and late insomnia in patients were 39.2%, 42.5%, and 48.3%, respectively, compared to 22.5%, 10.0%, and 25.0% in controls. Urban residency was independently associated with less insomnia of any type, accounting for 22.6% of the variance.

PRACTICE IMPLICATIONS

A considerable proportion of patients with HBV-related diseases suffer from insomnia that warrants more attention in clinical practice.

Agomelatine versus Sertraline: An Observational, Open-labeled and 12 Weeks Follow-up Study on Efficacy and Tolerability

Objective

In this open-labeled, 12 weeks follow-up study, we aimed to compare the efficacy and tolerability of agomelatine with sertraline

Methods

The outpatients of adult psychiatry clinic who have a new onset of depression and diagnosed as ‘major depressive episode’ by clinician according to the Diagnostic and Statistical Manual of Mental Disorders 4th edition and prescribed agomelatine (25 mg/day) or sertraline (50 mg/day) were included in the study.

Results

The decline of mean Montgomery-Asberg Depression Rating Scale (MADRS) scores of agomelatine group was significantly higher than the sertraline group at the end of 2nd week; however, the difference was not significant at the end of 3 months. Mean Clinical Global Impression-Improvement scale (CGI-I) scores of agomelatine group was lower than sertraline group at first week. Mean CGI-Severity scale and CGI-I scores were favour to sertraline group at the end of the study. Remission rates were 46.7% for sertraline group and 33.3% for agomelatine group while response rates were 76.7% for both groups. Any patient from agomelatine group dropped-out due to adverse effects. The amount of side effects was also less with agomelatine.

Conclusion

Agomelatine has a rapid onset efficacy on depressive symptoms and this can be beneficial for some critical cases. Considering MADRS scores, agomelatine seems to have similar efficacy with sertraline but we also point the need for long term studies since CGI scores were favour to sertraline group at the end of the study. Agomelatine has a favourable tolerability profile both in terms of discontinuation and the amount of side effects compared to sertraline.

Characterisation of Agomelatine-Induced Increase in Liver Enzymes: Frequency and Risk Factors Determined from a Pooled Analysis of 7605 Treated Patients

BACKGROUND

Antidepressant-induced liver injury is a major concern and a liver monitoring scheme has been recommended by the European Medicines Agency for agomelatine.

OBJECTIVE

The objective of this study was to assess the liver safety and identify the characteristics of patients who developed a significant increase in transaminases whilst taking agomelatine.

METHOD

A retrospective pooled analysis of changes in transaminase levels in 9234 patients treated with agomelatine (25 or 50 mg/day; n = 7605) or placebo (n = 1629) from 49 phase II and III studies was undertaken. A significant increase in transaminase levels was defined as an increase to >3 times the upper limit of normal (ULN) (>3 × ULN). Final causality was determined in a case-by-case review by five academic experts.

RESULTS

Serum transaminases increased to >3 × ULN in 1.3 and 2.5 % of patients treated with 25 and 50 mg of agomelatine, respectively, compared with 0.5 % for placebo. The onset of increased transaminases occurred before 12 weeks in 64 % of patients. The median time to recovery (to ≤2 × ULN) was 14 days following treatment withdrawal. Liver function tests recovered in 36.1 % of patients despite continuation of agomelatine, suggesting the presence of a liver adaptive mechanism. No cases of acute liver failure or fatal outcome occurred. Patients with elevated transaminases at baseline, secondary to obesity/fatty liver disease, had an equally increased risk of developing further elevations of transaminases with agomelatine and placebo.

CONCLUSION

Incidence of abnormal transaminases was low and dose dependent. No specific population was identified regarding potential risk factors. Withdrawal of agomelatine led to rapid recovery, and some patients exhibited an adaptive phenomenon. Overall, in clinical trials, the liver profile of agomelatine seems safe when serum transaminases are monitored.

Problems in the Descriptions of the Psychiatric Inclusion and Exclusion Criteria in Publications of Antidepressant Efficacy Trials: A Qualitative Review and Recommendations for Improved Clarity

We recently conducted a comprehensive review of the psychiatric inclusion and exclusion criteria used in 170 placebo-controlled antidepressant efficacy trials (AETs) that were published between 1995 and 2014. In conducting this literature review, we identified a number of instances in which the descriptions of the inclusion/exclusion criteria were vague, redundant, or difficult to interpret. In the present article, we describe nine problems we encountered in our literature review. We recommend that future publications follow the examples found in a few studies in which the inclusion/exclusion criteria are clearly defined and listed in a table.

Agomelatine Increases BDNF Serum Levels in Depressed Patients in Correlation with the Improvement of Depressive Symptoms

BACKGROUND

Agomelatine modulates brain-derived neurotrophic factor expression via its interaction with melatonergic and serotonergic receptors and has shown promising results in terms of brain-derived neurotrophic factor increase in animal models.

METHODS

Twenty-seven patients were started on agomelatine (25mg/d). Venous blood was collected and brain-derived neurotrophic factor serum levels were measured at baseline and after 2 and 8 weeks along with a clinical assessment, including Hamilton Depression Rating Scale and Snaith-Hamilton Pleasure Scale.

RESULTS

Brain-derived neurotrophic factor serum concentration increased after agomelatine treatment. Responders showed a significant increase in brain-derived neurotrophic factor levels after 2 weeks of agomelatine treatment; no difference was observed in nonresponders. Linear regression analysis showed that more prominent brain-derived neurotrophic factor level variation was associated with lower baseline BDNF levels and greater anhedonic features at baseline.

CONCLUSIONS

Patients affected by depressive disorders showed an increase of brain-derived neurotrophic factor serum concentration after a 2-week treatment with agomelatine. The increase of brain-derived neurotrophic factor levels was found to be greater in patients with lower brain-derived neurotrophic factor levels and marked anhedonia at baseline.

A Comparative Study of Efficacy and Safety of Agomelatine and Escitalopram in Major Depressive Disorder

BACKGROUND

Major depressive disorder (MDD) is a mental disorder characterized by episodes of depressed mood, loss of interest or pleasure, feeling of guilt or low self-esteem, loss of energy, altered sleep patterns and difficulty in concentration.

OBJECTIVE

This study was carried out to compare the efficacy and safety of Agomelatine with Escitalopram in the treatment of major depressive disorder.

DESIGN AND SETTING

This is a prospective study conducted at Outpatient Department of Psychiatry, GSL Medical College & General hospital, Rajahmundry, India.

MATERIALS AND METHODS

Patients with newly diagnosed major depressive disorder (DSM-IV-TR) with minimum score of 20 in Hamilton depression rating scale were randomly assigned Agomelatine (25-50 mg/day) or Escitalopram (10-20 mg/day) for a period of 8 weeks. The main efficacy outcome considered was the mean change of HAM-D17 score from baseline to end of therapy. Secondary outcome measures were Clinical Global Impressions-improvement (CGI) and severity (CGI-S) rating scales.

STATISTICAL ANALYSIS

Student t-test was used for comparing the groups and chi-square test was used for assessing the qualitative variables. For all statistical analysis p<0.05 was considered statistically significant.

RESULTS

The drugs under study effectively reduced depressive symptoms at all the time points. The percentage of responders at 8weeks (last post baseline value) was 65.38% with Agomelatine and 57.40% with Escitalopram. The difference between the drugs was statistically not significant in all evaluations (p>0.05). The mean CGI-S and CGI-I scores were decreased in both the groups (p<0.05) and there was no statistically significant difference between the groups at any assessment during the study period. Both the treatment groups showed favourable safety profile.

CONCLUSION

The study results supported that Agomelatine is therapeutically similar to Escitalopram in terms of antidepressant effect.

Agomelatine or ramelteon as treatment adjuncts in glioblastoma and other M1- or M2-expressing cancers

The impressive but sad list of over forty clinical studies using various cytotoxic chemotherapies published in the last few years has failed to increase median survival of glioblastoma beyond two years after diagnosis. In view of this apparent brick wall, adjunctive non-cytotoxic growth factor blocking drugs are being tried, as in the CUSP9* protocol. A related theme is searching for agonists at growth inhibiting receptors. One such dataset is that of melatonin agonism at M1 or M2 receptors found on glioblastoma cells, being a negative regulator of these cells’ growth. Melatonin itself is an endogenous hormone, but when used as an exogenously administered drug it has many disadvantages. Agomelatine, marketed as an antidepressant, and ramelteon, marketed as a treatment for insomnia, are currently-available melatonin receptor agonists. These melatonin receptor agonists have significant advantages over the natural ligand: longer half-life, better oral absorption, and higher affinity to melatonin receptors. They have an eminently benign side effect profile. As full agonists they should function to inhibit glioblastoma growth, as demonstrated for melatonin. A potentially helpful ancillary attribute of melatonergic agonists in glioblastoma treatment is an increase in interleukin-2 synthesis, expected, at least partially, to reverse some of the immunosuppression associated with glioblastoma.

A systematic review of agomelatine-induced liver injury

Agomelatine is an antidepressant with a unique mechanism of action. Since its marketing in 2009, concerns have been raised regarding its potential to induce liver injury. The authors therefore address the need to comprehensively evaluate the potential risk posed by agomelatine of inducing liver injury by reviewing data from published and unpublished clinical trials in both the pre- and postmarketing settings, as well as data from non-interventional studies, pharmacovigilance database reviews and one case report. Recommendations for clinicians are also provided.

In this review, agomelatine was found to be associated with higher rates of liver injury than both placebo and the four active comparator antidepressants used in the clinical trials for agomelatine, with rates as high as 4.6% for agomelatine compared to 2.1% for placebo, 1.4% for escitalopram, 0.6% for paroxetine, 0.4% for fluoxetine, and 0% for sertraline. The review also provides evidence for the existence of a positive relationship between agomelatine dose and liver injury. Furthermore, rates of liver injury were found to be lower in non-interventional studies. Findings from pharmacovigilance database reviews and one case report also highlight the risk of agomelatine-induced liver injury.

As agomelatine does pose a risk of liver injury, clinicians must carefully monitor liver function throughout treatment. However, agomelatine’s unique mechanism of action and favourable safety profile render it a valuable treatment option.

A quantitative analysis of agomelatine-induced liver injury is lacking in the literature and would be welcomed.

Combination of agomelatine and bupropion for treatment-resistant depression: results from a chart review study including a matched control group

INTRODUCTION

Although a growing selection of antidepressants is available, a significant number of patients do not reach clinical remission, despite multiple trials. Data concerning the efficacy and safety of combination therapies with newer antidepressants are limited.

METHODS

Fifteen inpatients with treatment-resistant depression (TRD), defined as Beck Depression Inventory-2 (BDI-2) scores >14 despite treatment with adequate doses of ≥ 1 antidepressant classes for ≥ 6 weeks, were treated with agomelatine plus bupropion for ≥6 weeks, and compared to 15 patients on antidepressant monotherapy with TRD matched on age, sex, and TRD stage based on retrospective chart review. The primary outcome was change in BDI-2 scores. Secondary outcomes included treatment response (BDI-2 score decrease by ≥ 50%), remission (BDI-2 score <13), routinely measured cardiometabolic parameters and adverse effects.

RESULTS

After a mean of 6 ± 1 weeks, BDI-2 scores decreased by 20.3 ± 5.6 points in the combination group compared to 12.5 ± 15.1 points in the monotherapy group (P = 0.073; Cohen's d = 0.7). Altogether, 73.3% in the combination group responded compared to 53.3% on monotherapy (P = 0.27). About 60.0% on combination therapy reached remission compared to 40% on monotherapy (P = 0.28), a difference equivalent to a number-needed-to-treat = 4. Treatment response was independent of the degree of TRD (P = 0.27). Bupropion-agomelatine cotreatment was well tolerated and laboratory adverse effect parameters were not altered.

CONCLUSION

Despite the small sample and uncontrolled study design, the good remission rate in TRD patients receiving agomelatine plus bupropion, particularly in comparison to the monotherapy group, indicates that this combination treatment should be explored further as a potentially promising strategy for patients with TRD.

Profile of agomelatine and its potential in the treatment of generalized anxiety disorder

BACKGROUND

Although many generalized anxiety disorder (GAD) patients respond to the available pharmacological treatments, nearly half of them do not present the expected results. Besides, the side effects associated to some drugs have a negative impact on treatment adherence. Therefore, the aim of this review was to report the clinical profile of agomelatine, a selective melatonergic MT1/MT2 receptor agonist with serotonin 5-HT2c receptor antagonist activities, as a potential pharmacological option in the treatment of GAD.

METHODS

We performed a literature review regarding studies that evaluated the use of agomelatine in GAD treatment.

RESULTS

Two short-term, double-blinded studies and one prevention-treatment trial evaluated the efficacy of agomelatine in the treatment of GAD. Agomelatine was associated with higher rates of clinical response and remission, when compared to placebo. In addition, the long-term use of agomelatine decreased the risk of relapse of anxiety symptoms, even for the severely ill patients. Besides, the tolerability was satisfactory with the absence of discontinuation symptoms, as observed in previous studies.

CONCLUSION

The efficacy and tolerability profiles of agomelatine in the treatment of GAD were good. However, the scarce number of trials, the small sample sizes, and the use of patients without any comorbid conditions were some limitations that impaired the generalization of the results in the general population. Nevertheless, agomelatine is an attractive off-label option in the treatment of GAD that needs more conclusive evidences to establish its role in future guidelines.

Agomelatine in the treatment of major depressive disorder: an assessment of benefits and risks

Agomelatine (AGM) was approved for the treatment of major depressive disorder (MDD) in adults by the European Medicines Agency (EMA) in February 2009. It is an analogue of melatonin and features a unique pharmacodynamic profile with agonism on both types of melatonergic receptors (MT1/MT2) and antagonism at serotonergic 5-HT2C receptors. There is, however, an ongoing debate regarding the efficacy and safety of this novel antidepressant agent, originally evoked by claims of a significant publication bias underlying the assessment of AGM being an effective antidepressant. Indeed, two recent comprehensive metaanalyses of published and unpublished clinical trials found evidence for a relevant publication bias. However, due to its statistically significant advantage over placebo based on the results of these metaanalyses AGM must be referred to as an effective antidepressant agent in the acute phase of MDD. However, the effect sizes of AGM in the treatment of MDD were evaluated as being small in comparison to other antidepressant agents. In addition, there is insufficient evidence for the efficacy of AGM in relapse prevention of MDD. Apart from efficacy issues, AGM appears to have the potential to exhibit severe hepatotoxicity (the EMA has identified AGM-associated “hepatotoxic reactions” as a new safety concern in September 2013) that is currently poorly understood. Considering these aspects, it seems inappropriate to evaluate AGM as an antidepressant agent of first choice. Nevertheless, its unique mechanism of action with particular sleep modulating effects may represent a specific treatment strategy for patients with particular characteristics; further studies with thorough characterization of patients are needed to test this hypothesis.

Antidepressant efficacy of agomelatine: meta-analysis of published and unpublished studies

OBJECTIVE

To systematically review published and unpublished efficacy studies of agomelatine in people with depression.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Literature search (Pubmed, Embase, Medline), Cochrane Central Register of Controlled Trials, European Medicines Agency (EMA) regulatory file for agomelatine, manufacturers of agomelatine (Servier).

ELIGIBILITY CRITERIA

Double blind randomised placebo and comparator controlled trials of agomelatine in depression with standard depression rating scales.

DATA SYNTHESIS

Studies were pooled by using a random effects model with DerSimonian and Laird weights for comparisons with placebo and comparator antidepressant. The primary efficacy measure (change in rating scale score) was summarised with standardised mean difference (SMD; a measure of effect size) and secondary outcome measures with relative risks. All results were presented with 95% confidence intervals. Statistical heterogeneity was explored by visual inspection of funnel plots and by the I(2) statistic. Moderators of effect were explored by meta-regression.

RESULTS

We identified 20 trials with 7460 participants meeting inclusion criteria (11 in the published literature, four from the European Medicines Agency file, and five from the manufacturer). Almost all studies used the 17 item Hamilton depression rating scale (score 0-50). Agomelatine was significantly more effective than placebo with an effect size (SMD) of 0.24 (95% confidence interval 0.12 to 0.35) and relative risk of response 1.25 (1.11 to 1.4). Compared with other antidepressants, agomelatine showed equal efficacy (SMD 0.00, -0.09 to 0.10). Significant heterogeneity was uncovered in most analyses, though risk of bias was low. Published studies were more likely than unpublished studies to have results that suggested advantages for agomelatine.

CONCLUSIONS

Agomelatine is an effective antidepressant with similar efficacy to standard antidepressants. Published trials generally had more favourable results than unpublished studies.

Efficacy and tolerability of agomelatine in the treatment of depression

Depression is a severe and usually recurrent mental disorder which often leads to a significant impairment of everyday functioning, a reduced quality of life, and also great suffering of the patients. The treatment of a depressive disorder is not only limited to acute treatment; it also requires prolonged management. Patient compliance is of utmost importance. Unpleasant adverse effects and their impact on everyday living often lead to a premature discontinuation of antidepressant treatment and result in an unfavorable treatment outcome. The new antidepressant agomelatine, a melatonergic MT1/MT2 agonist and 5-HT2C receptor antagonist, has exhibited good antidepressant efficacy in acute, short-term, and long-term treatment. The adverse effect profile of agomelatine has been proven to be favorable and comparable to placebo, which is very important for good treatment compliance and adherence.

Agomelatine in the treatment of depressive disorders in clinical practice: multicenter observational CHRONOS study

BACKGROUND

CHRONOS was a large naturalistic study designed to evaluate the effectiveness and safety of agomelatine in the management of patients with major depression in routine clinical practice.

METHODS

Patients (n=6,276) with a moderate or severe major depressive episode without psychotic symptoms were treated initially as outpatients (80.2%) or in psychiatric facilities (19.8%) in 54 regions of the Russian Federation. Patients received a flexible-dosing regimen of agomelatine 25 mg or 50 mg once daily for 8 weeks, with frequent study visits (weeks 1, 2, 3, 4, 6, and 8).

RESULTS

Patients (mean age 44 years, 72.6% female) showed progressive improvement on the 17-item Hamilton Rating Scale for Depression (HAMD-17) total score from 22±6.9 at baseline to 4.7±4.7 at week 8 (P<0.0001). The proportion of responders (HAMD-17 decrease of ≥50%) was 90.1% and the proportion of remitters (HAMD-17 <7) was 79.1% at week 8. All individual HAMD-17 item scores improved rapidly, and the change relative to baseline was significant (P<0.0001) at week 1 and at each subsequent visit in all cases. There were corresponding rapid improvements in Clinical Global Impression Severity and Improvement scores. In the subgroup of patients with more severe illness (HAMD-17 ≥21 at baseline; n=3,478), the proportions of responders and remitters were 92.4% and 72.8%, respectively, at week 8.

CONCLUSION

Agomelatine was effective and well tolerated in a large sample of depressed patients in an observational treatment setting, and showed a rapid onset of benefit across all HAMD-17 items.

The melatonergic system in mood and anxiety disorders and the role of agomelatine: implications for clinical practice

Melatonin exerts its actions through membrane MT1/MT2 melatonin receptors, which belong to the super family of G-protein-coupled receptors consisting of the typical seven transmembrane domains. MT1 and MT2 receptors are expressed in various tissues of the body either as single ones or together. A growing literature suggests that the melatonergic system may be involved in the pathophysiology of mood and anxiety disorders. In fact, some core symptoms of depression show disturbance of the circadian rhythm in their clinical expression, such as diurnal mood and other symptomatic variation, or are closely linked to circadian system functioning, such as sleep-wake cycle alterations. In addition, alterations have been described in the circadian rhythms of several biological markers in depressed patients. Therefore, there is interest in developing antidepressants that have a chronobiotic effect (i.e., treatment of circadian rhythm disorders). As melatonin produces chronobiotic effects, efforts have been aimed at developing agomelatine, an antidepressant with melatonin agonist activity. The present paper reviews the role of the melatonergic system in the pathophysiology of mood and anxiety disorders and the clinical characteristics of agomelatine. Implications of agomelatine in "real world" clinical practice will be also discussed.

Agomelatine as monotherapy for major depression: an outpatient, open-label study

BACKGROUND

Agomelatine is a novel antidepressant agonist to MT1 and MT2 subtypes of melatoninergic receptors (MT1 and MT2) and antagonist to 5-HT2C subtype of serotonergic (5-HT2C) receptors, which has shown antidepressant efficacy in short-term and long-term trials as well as in clinical practice. The purpose of this study was to assess the antidepressant efficacy, safety, and the influence of agomelatine on the functioning of patient in common clinical practice.

METHODS

In this open-label, 8-week, multicenter, Phase IV trial, 111 patients with mainly moderate to severe major depressive disorder (39% treatment-naïve) were treated with agomelatine 25-50 mg/day for up to 8 weeks. The primary endpoint was the mean change in total Montgomery and Åsberg Depression Rating Scale (MADRS). Secondary endpoints included assessment of clinical response (defined as a reduction in total MADRS score of ≥50%), and change in Clinical Global Impression scales, Global Assessment of Functioning scale, Sheehan Disability Scale, and CircScreen sleep questionnaire scores. Safety and tolerability were also monitored.

RESULTS

Of the 111 patients enrolled, 94 completed the study. The total MADRS score significantly decreased by the first week of treatment and continued to decline significantly until study completion, with an estimated mean change of 3.9 ± 3.9 and 17.2 ± 8.0 at the first and eighth week of the study (last observation carried forward analyses). All other secondary endpoints significantly improved from early treatment evaluation to study completion. A clinical response was observed in 14.1% of patients after the first week, rising to 74.5% of patients at study completion. There were 31 spontaneously reported adverse events in 17 patients, and most were mild to moderate in severity.

CONCLUSION

This study showed good short-term efficacy for agomelatine in outpatients with major depressive episodes. Treatment with agomelatine achieved early and consistent responses for symptoms of depression and other dimensions of clinical and functional status. Agomelatine achieved significant improvements in daily functioning of patients, and had good tolerability. Clinically, no hepatic events were observed.

5-HT2C receptors in the basolateral amygdala and dorsal striatum are a novel target for the anxiolytic and antidepressant effects of exercise

Physical activity reduces the incidence and severity of psychiatric disorders such as anxiety and depression. Similarly, voluntary wheel running produces anxiolytic- and antidepressant-like effects in rodent models. The specific neurobiological mechanisms underlying the beneficial properties of exercise, however, remain unclear. One relevant pharmacological target in the treatment of psychiatric disorders is the 5-HT(2C) receptor (5-HT(2C)R). Consistent with data demonstrating the anxiogenic consequences of 5-HT(2C)R activation in humans and rodents, we have previously reported that site-specific administration of the selective 5-HT(2C)R agonist CP-809101 in the lateral/basolateral amygdala (BLA) increases shock-elicited fear while administration of CP-809101 in the dorsal striatum (DS) interferes with shuttle box escape learning. These findings suggest that activation of 5-HT(2C)R in discrete brain regions contributes to specific anxiety- and depression-like behaviors and may indicate potential brain sites involved in the anxiolytic and antidepressant effects of exercise. The current studies tested the hypothesis that voluntary wheel running reduces the behavioral consequences of 5-HT(2C)R activation in the BLA and DS, specifically enhanced shock-elicited fear and interference with shuttle box escape learning. After 6 weeks of voluntary wheel running or sedentary conditions, the selective 5-HT(2C)R agonist CP-809101 was microinjected into either the BLA or the DS of adult Fischer 344 rats, and shock-elicited fear and shuttle box escape learning was assessed. Additionally, in-situ hybridization was used to determine if 6 weeks of voluntary exercise changed levels of 5-HT(2C)R mRNA. We found that voluntary wheel running reduced the behavioral effects of CP-809101 and reduced levels of 5-HT(2C)R mRNA in both the BLA and the DS. The current data indicate that expression of 5-HT(2C)R mRNA in discrete brain sites is sensitive to physical activity status of the organism, and implicates the 5-HT(2C)R as a target for the beneficial effects of physical activity on mental health.

Agomelatine (S20098) modulates the expression of cytoskeletal microtubular proteins, synaptic markers and BDNF in the rat hippocampus, amygdala and PFC

RATIONALE

Agomelatine is described as a novel and clinical effective antidepressant drug with melatonergic (MT(1)/MT(2)) agonist and 5-HT(2C) receptor antagonist properties. Previous studies suggest that modulation of neuronal plasticity and microtubule dynamics may be involved in the treatment of depression.

OBJECTIVE

The present study investigated the effects of agomelatine on microtubular, synaptic and brain-derived neurotrophic factor (BDNF) proteins in selected rat brain regions.

METHODS

Adult male rats received agomelatine (40 mg/kg i.p.) once a day for 22 days. The pro-cognitive effect of agomelatine was tested in the novel object recognition task and antidepressant activity in the forced swimming test. Microtubule dynamics markers, microtubule-associated protein type 2 (MAP-2), phosphorylated MAP-2, synaptic markers [synaptophysin, postsynaptic density-95 (PSD-95) and spinophilin] and BDNF were measured by Western blot in the hippocampus, amygdala and prefrontal cortex (PFC).

RESULTS

Agomelatine exerted pro-cognitive and antidepressant activity and induced molecular changes in the brain areas examined. Agomelatine enhanced microtubule dynamics in the hippocampus and to a higher magnitude in the amygdala. By contrast, in the PFC, a decrease in microtubule dynamics was observed. Spinophilin (dendritic spines marker) was decreased, and BDNF increased in the hippocampus. Synaptophysin (presynaptic) and spinophilin were increased in the PFC and amygdala, while PSD-95 (postsynaptic marker) was increased in the amygdala, consistent with the phenomena of synaptic remodelling.

CONCLUSIONS

Agomelatine modulates cytoskeletal microtubule dynamics and synaptic markers. This may play a role in its pharmacological behavioural effects and may result from the melatonergic agonist and 5-HT(2C) antagonist properties of the compound.

Melatonin receptor agonists: new options for insomnia and depression treatment

The circadian nature of melatonin (MLT) secretion, coupled with the localization of MLT receptors to the suprachiasmatic nucleus, has led to numerous studies of the role of MLT in modulation of the sleep-wake cycle and circadian rhythms in humans. Although much more needs to be understood about the various functions exerted by MLT and its mechanisms of action, three therapeutic agents (ramelteon, prolonged-release MLT, and agomelatine) are already in use, and MLT receptor agonists are now appearing as new promising treatment options for sleep and circadian-rhythm related disorders. In this review, emphasis has been placed on medicinal chemistry strategies leading to MLT receptor agonists, and on the evidence supporting therapeutic efficacy of compounds undergoing clinical evaluation. A wide range of clinical trials demonstrated that ramelteon, prolonged-release MLT and tasimelteon have sleep-promoting effects, providing an important treatment option for insomnia and transient insomnia, even if the improvements of sleep maintenance appear moderate. Well-documented effects of agomelatine suggest that this MLT agonist offers an attractive alternative for the treatment of depression, combining efficacy with a favorable side effect profile. Despite a large number of high affinity nonselective MLT receptor agonists, only limited data on MT₁ or MT₂ subtype-selective compounds are available up to now. Administration of the MT₂-selective agonist IIK7 to rats has proved to decrease NREM sleep onset latency, suggesting that MT₂ receptor subtype is involved in the acute sleep-promoting action of MLT; rigorous clinical studies are needed to demonstrate this hypothesis. Further clinical candidates based on selective activation of MT₁ or MT₂ receptors are expected in coming years.

Major depressive disorder: new clinical, neurobiological, and treatment perspectives

In this Seminar we discuss developments from the past 5 years in the diagnosis, neurobiology, and treatment of major depressive disorder. For diagnosis, psychiatric and medical comorbidity have been emphasised as important factors in improving the appropriate assessment and management of depression. Advances in neurobiology have also increased, and we aim to indicate genetic, molecular, and neuroimaging studies that are relevant for assessment and treatment selection of this disorder. Further studies of depression-specific psychotherapies, the continued application of antidepressants, the development of new treatment compounds, and the status of new somatic treatments are also discussed. We address two treatment-related issues: suicide risk with selective serotonin reuptake inhibitors, and the safety of antidepressants in pregnancy. Although clear advances have been made, no fully satisfactory treatments for major depression are available.

Mood disorders, circadian rhythms, melatonin and melatonin agonists

Recent advances in the understanding of circadian rhythms have led to an interest in the treatment of major depressive disorder with chronobiotic agents. Many tissues have autonomous circadian rhythms, which are orchestrated by the master clock, situated in the suprachiasmatic nucleus (SNC). Melatonin (N-acetyl-5-hydroxytryptamine) is secreted from the pineal gland during darkness. Melatonin acts mainly on MT1 and MT2 receptors, which are present in the SNC, regulating physiological and neuroendocrine functions, including circadian entrainment, referred to as the chronobiotic effet. Circadian rhythms has been shown to be either misaligned or phase shifted or decreased in amplitude in both acute episodes and relapse of major depressive disorder (MDD) and bipolar disorder. Manipulation of circadian rhythms either using physical treatments (such as high intensity light) or behavioral therapy has shown promise in improving symptoms. Pharmacotherapy using melatonin and pure melatonin receptor agonists, while improving sleep, has not been shown to improve symptoms of depression. A novel antidepressant, agomelatine, combines 5HT2c antagonist and melatonin agonist action, and has shown promise in both acute treatment of MDD and in preventing relapse.

Neuroimmune endocrine effects of antidepressants

Antidepressant pharmacotherapy is to date the most often used treatment for depression, but the exact mechanism of action underlying its therapeutic effect is still unclear. Many theories have been put forward to account for depression, as well as antidepressant activity, but none of them is exhaustive. Neuroimmune endocrine impairment is found in depressed patients; high levels of circulating corticosteroids along with hyperactivation of the immune system, high levels of proinflammatory cytokines, low levels of melatonin in plasma and urine, and disentrainment of circadian rhythms have been demonstrated. Moreover, antidepressant treatment seems to correct or at least to interfere with these alterations. In this review, we summarize the complex neuroimmune endocrine and chronobiological alterations found in patients with depression and how these systems interact with each other. We also explain how antidepressant therapy can modify these systems, along with some possible mechanisms of action shown in animal and human models.

Agomelatine in unipolar depression in clinical practice: a retrospective chart review

Agomelatine (Valdoxan), a synthetic melatonergic receptor agonist at the MT1 and MT2 receptors, was first used in the management of sleep disorder. Its 5HT2C receptor antagonistic properties support its antidepressant potential. It is currently licensed in the UK, Europe and USA for the treatment of major depressive disorder. Although the randomized controlled evidence base for its use is growing, there are no retrospective, naturalistic studies available. We aimed to determine the tolerability and clinical effectiveness of agomelatine in unipolar depression. We also examined whether being refractory to treatment altered clinical outcome. Forty-eight patient records were examined. Twenty-five percent were treatment refractory: Clinical Global Impression (CGI) Severity score at the start of treatment was 3.81 compared with 3.38 at the end of treatment. Fifty-four percent improved at least minimally; only 12.5% were much or very much improved. Treatment-refractory patients had a poorer outcome with higher discontinuation rates and lower CGI Improvement (p = 0.0205). Treatment-refractory patients also had a higher CGI Severity score at the end of treatment than at treatment commencement (3.92 versus 3.75), although this was not statistically significant.

5-hydroxytryptamine 2C receptors in the dorsal striatum mediate stress-induced interference with negatively reinforced instrumental escape behavior

Uncontrollable stress can interfere with instrumental learning and induce anxiety in humans and rodents. While evidence supports a role for serotonin (5-HT) and serotonin 2C receptors (5-HT(2C)R) in the behavioral consequences of uncontrollable stress, the specific sites of action are unknown. These experiments sought to delineate the role of 5-HT and 5-HT(2C)R in the dorsal striatum (DS) and the lateral/basolateral amygdala (BLA) in the expression of stress-induced instrumental escape deficits and exaggerated fear, as these structures are critical to instrumental learning and fear behaviors. Using in vivo microdialysis, we first demonstrated that prior uncontrollable, but not controllable, stress sensitizes extracellular 5-HT in the dorsal striatum, a result that parallels prior work in the BLA. Additionally, rats were implanted with bi-lateral cannula in either the DS or the BLA and exposed to uncontrollable tail shock stress. One day later, rats were injected with 5-HT(2C)R antagonist (SB242084) and fear and instrumental learning behaviors were assessed in a shuttle box. Separately, groups of non-stressed rats received an intra-DS or an intra-BLA injection of the 5-HT(2C)R agonist (CP809101) and behavior was observed. Intra-DS injections of the 5-HT(2C)R antagonist prior to fear/escape tests completely blocked the stress-induced interference with instrumental escape learning; a partial block was observed when injections were in the BLA. Antagonist administration in either region did not influence stress-induced fear behavior. In the absence of prior stress, intra-DS administration of the 5-HT(2C)R agonist was sufficient to interfere with escape behavior without enhancing fear, while intra-BLA administration of the 5-HT(2C)R agonist increased fear behavior but had no effect on escape learning. Results reveal a novel role of the 5-HT(2C)R in the DS in the expression of instrumental escape deficits produced by uncontrollable stress and demonstrate that the involvement of 5-HT(2C)R activation in stress-induced behaviors is regionally specific.

A systematic, updated review on the antidepressant agomelatine focusing on its melatonergic modulation

Objective:

To present an updated, comprehensive review on clinical and pre-clinical studies on agomelatine.

Method:

A MEDLINE, Psycinfo and Web of Science search (1966-May 2009) was performed using the following keywords: agomelatine, melatonin, S20098, efficacy, safety, adverse effect, pharmacokinetic, pharmacodynamic, major depressive disorder, bipolar disorder, Seasonal Affective Disorder (SAD), Alzheimer, ADHD, Generalized Anxiety Disorder (GAD), Panic Disorder (PD), Obsessive-Compulsive Disorder (OCD), anxiety disorders and mood disorder.

Study collection and data extraction:

All articles in English identified by the data sources were evaluated. Randomized, controlled clinical trials involving humans were prioritized in the review. The physiological bases of melatonergic transmission were also examined to deepen the clinical comprehension of agomelatine’ melatonergic modulation.

Data synthesis:

Agomelatine, a melatonergic analogue drug acting as MT₁/MT₂ agonist and 5-HT_2C antagonist, has been reported to be an effective antidepressant therapy.

Conclusions:

Although a bias in properly assessing the “sleep core” of depression may still exist with current screening instruments, therefore making difficult to compare agomelatine’ efficacy to other antidepressant ones, comparative studies showed agomelatine to be an intriguing option for depression and, potentially, for other therapeutic targets as well.

ACS chemical neuroscience molecule spotlight on Valdoxen

A new and novel non-SSRI potential treatment option for major depressive disorders is Valdoxen (agomelatine) which is currently in phase III clinical studies. Valdoxen is a norepinephrine disinhibitor (NNDI) and is also an antagonist of the 5-HT(2C) receptor.

International Union of Basic and Clinical Pharmacology. LXXV. Nomenclature, classification, and pharmacology of G protein-coupled melatonin receptors

The hormone melatonin (5-methoxy-N-acetyltryptamine) is synthesized primarily in the pineal gland and retina, and in several peripheral tissues and organs. In the circulation, the concentration of melatonin follows a circadian rhythm, with high levels at night providing timing cues to target tissues endowed with melatonin receptors. Melatonin receptors receive and translate melatonin's message to influence daily and seasonal rhythms of physiology and behavior. The melatonin message is translated through activation of two G protein-coupled receptors, MT(1) and MT(2), that are potential therapeutic targets in disorders ranging from insomnia and circadian sleep disorders to depression, cardiovascular diseases, and cancer. This review summarizes the steps taken since melatonin's discovery by Aaron Lerner in 1958 to functionally characterize, clone, and localize receptors in mammalian tissues. The pharmacological and molecular properties of the receptors are described as well as current efforts to discover and develop ligands for treatment of a number of illnesses, including sleep disorders, depression, and cancer.

Agomelatine: The evidence for its place in the treatment of depression

INTRODUCTION

Depressive disorders are among the main causes of disability due to disease. In spite of recent progress in the pharmacotherapy of depression, there is still a high nonresponse rate of approximately 30% to the first antidepressant treatment. Furthermore, the latency of several weeks until sufficient clinical improvement and the risk of side effects remain unresolved problems. Therefore, there is still further need for the development of new antidepressants. In the last years a variety of melatonin receptor agonists have been synthesized and evaluated for the treatment of sleep disorders. Animal studies suggested that agomelatine (S-20098), a synthetic melatonergic MT(1) and MT(2) receptor agonist with serotonin receptor antagonistic properties, may have additional activating properties and may represent a new approach in the treatment of depression.

AIMS

Clinical trials that have demonstrated efficacy and safety of agomelatine for the treatment of depression are reviewed.

EVIDENCE REVIEW

In clinical trials, including phase III studies, superior efficacy compared to placebo and good efficacy compared to standard antidepressants was shown for agomelatine for the acute treatment of major depression. In all studies published so far agomelatine was safe and the overall tolerability profile was superior to selective serotonin reuptake inhibitors or selective serotonin and norepinephrine reuptake inhibitors.

PLACE IN THERAPY

Agomelatine may represent a novel perspective in the treatment of acute depression. The improvement of sleep disturbances, the tolerability in terms of sexual side effects, and the lack of withdrawal symptoms after abrupt discontinuation of treatment may represent important clinical benefits compared to established antidepressants.

Blockade of stress-induced increase of glutamate release in the rat prefrontal/frontal cortex by agomelatine involves synergy between melatonergic and 5-HT2C receptor-dependent pathways

Background

Agomelatine is a melatonergic receptor agonist and a 5HT_2C receptor antagonist that has shown antidepressant efficacy. In order to analyze separately the effect of the two receptorial components, rats were chronically treated with agomelatine, melatonin (endogenous melatonergic agonist), or S32006 (5-HT_2C antagonist), and then subjected to acute footshock-stress.

Results

Only chronic agomelatine, but not melatonin or S32006, completely prevented the stress-induced increase of glutamate release in the rat prefrontal/frontal cortex.

Conclusions

These results suggest a potential synergy between melatonergic and serotonergic pathways in the action of agomelatine.

Pharmacologic approaches to treatment resistant depression: a re-examination for the modern era

IMPORTANCE OF THE FIELD

Treatment-resistant depression (TRD) is common and debilitating. Initial treatment is often insufficient to achieve full remission in a given depressive episode, resulting in more frequent episodes, worsened severity, and major disability.

AREAS COVERED IN THIS REVIEW

This review surveys literature on the diagnosis and pharmacological management of TRD in light of recent developments. Evidence regarding commonly used treatment options is critically examined and key recommendations are offered. The review ends by considering drugs acting on the melatonin, acetylcholine, and glutamate systems that hold promise as future options for TRD.

WHAT THE READER WILL GAIN

Recent trends and research findings have impacted how the evidence supporting different approaches to TRD should be evaluated. For example, many earlier TRD studies employed tricyclics as the primary antidepressant, but tricyclics have now been superseded by selective serotonin reuptake inhibitors (SSRIs) in routine clinical practice. This deficiency has been addressed by the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study, the largest effectiveness study of TRD ever conducted. However, design characteristics of the STAR*D study preclude simple comparisons with earlier studies.

TAKE HOME MESSAGE

A shortcoming of most treatment recommendations for TRD is their reliance on older studies that do not reflect the current preeminence of SSRIs in clinical practice. This has distorted the prioritization of pharmacological strategies for TRD. Efforts to correct this distortion with effectiveness research, designed to better reflect current practice trends, require critical consideration of the strengths and limitations of this approach.

Does effective management of sleep disorders reduce depressive symptoms and the risk of depression?

The link between co-morbid insomnia and depression has been demonstrated in numerous groups. Insomnia has been associated with: (1) an increased risk of developing subsequent depression; (2) an increased duration of established depression; and (3) relapse following treatment for depression. In addition, specific insomnia symptoms, such as nocturnal awakening with difficulty resuming sleep, are more strongly associated with depression than classic symptoms of insomnia. Participants of a workshop, held at the 6th annual meeting of The International Sleep Disorders Forum: The Art of Good Sleep in 2008, evaluated whether the effective management of sleep disorders could reduce both concurrent depressive symptoms and the risk of developing subsequent depression. Following the workshop, a targeted literature review was conducted. Initial evidence demonstrated that in patients with insomnia and co-morbid depression either pharmacological treatment of insomnia or psychological treatment in the form of cognitive behavioural therapy for insomnia improved both insomnia and depressive symptoms. Although these appeared to be promising treatment strategies, however, of the 27 identified treatment studies, only one large well-designed randomized controlled trial comparing the efficacy of eszopiclone plus fluoxetine with placebo plus fluoxetine demonstrated unequivocal evidence that improvements in insomnia symptoms conferred additive benefits on depressive outcomes. In addition, it was unclear whether any differences exist in efficacy between sedating versus non-sedating pharmacotherapies for insomnia in this patient group. Further studies of sufficient sample size and duration are needed to evaluate combinations of pharmacological (either sedating or non-sedating) and psychological interventions in co-morbid insomnia and depression. This article reviews the level of evidence, recommendations and areas of particular interest for further study and discussion arising from this workshop.

The novel antidepressant agomelatine normalizes hippocampal neuronal activity and promotes neurogenesis in chronically stressed rats

Agomelatine is a novel antidepressant which acts as a melatonergic (MT1/MT2) receptor agonist and serotonergic (5-HT2C) receptor antagonist. The antidepressant properties of agomelatine have been demonstrated in animal models as well as in clinical studies. Several preclinical studies reported agomelatine-induced effects on brain plasticity, mainly under basal conditions in healthy animals. Yet, it is important to unravel agomelatine-mediated changes in the brain affected by psychopathology or exposed to conditions that might predispose to mood disorders. Since stress is implicated in the etiology of depression, it is valid to investigate antidepressant-induced effects in animals subjected to chronic stress. In this context, we sought to determine changes in the brain after agomelatine treatment in chronically stressed rats. Adult male rats were subjected to footshock stress and agomelatine treatment for 21 consecutive days. Rats exposed to footshock showed a robust increase in adrenocorticotropic hormone (ACTH) and corticosterone. Chronic agomelatine treatment did not markedly influence this HPA-axis response. Whereas chronic exposure to daily footshock stress reduced c-Fos expression in the hippocampal dentate gyrus, agomelatine treatment reversed this effect and normalized neuronal activity to basal levels. Moreover, chronic agomelatine administration was associated with enhanced hippocampal cell proliferation and survival in stressed but not in control rats. Furthermore, agomelatine reversed the stress-induced decrease in doublecortin expression in the dentate gyrus. Taken together, these data show a beneficial action of agomelatine in the stress-compromised brain, where it restores stress-affected hippocampal neuronal activity and promotes adult hippocampal neurogenesis.

Critical appraisal and update on the clinical utility of agomelatine, a melatonergic agonist, for the treatment of major depressive disease in adults

This article describes the pharmacology of the novel atypical antidepressant drug agomelatine, critically reviews and evaluates its clinical use for the treatment of major depression, and suggests areas for further research. Agomelatine is a synthetic analog of the hormone melatonin. It stimulates the activity of melatonin MT1 and MT2 receptors and inhibits the activity of serotonin 5HT-2C receptor subtypes. Three acute trials demonstrated clinically modest, but statistically significant benefits over placebo. Three acute trials did not find agomelatine more effective than placebo. A meta-analysis of these six trials demonstrated a small, statistically significant, marginally clinically relevant difference between agomelatine and placebo. The only placebo-controlled study in elderly patients did not demonstrate a significant benefit for agomelatine. It was more effective than placebo in only one of two relapse prevention studies. Agomelatine was generally well tolerated compared to placebo. Its side-effect profile is different than and compares favorably to other antidepressant drugs. The overall tolerability of agomelatine in head-to-head comparisons was not substantially better than active drug comparators. Agomelatine is contraindicated in patients with impaired liver function and in patients taking drugs that potently inhibit CYP-1A2 metabolic enzymes. Because elevated liver enzymes are common, and there is a rare risk of more serious liver reactions, routine laboratory monitoring of liver function is recommended periodically throughout treatment. Agomelatine does not have clinically significant advantages compared to other antidepressant drugs, and it has certain limitations and disadvantages. Because of its unique pharmacology and relatively benign tolerability profile, however, it may be a useful alternative for patients who do not respond to or cannot tolerate other antidepressant drugs.

Insomnia in patients with depression: some pathophysiological and treatment considerations

The almost ubiquitous sleep disturbances in patients with depression commonly, but not always, subside with the remission of depression. Evidence linking insomnia with the risk of relapses in recurrent depression, as well as suicide, makes optimization of the treatment of insomnia associated with depression a priority. However, most antidepressant agents do not adequately address the sleep complaints in depression: their effects on sleep range from sizeable improvement to equally significant worsening. One approach to the management of insomnia associated with depression is to choose a sedating antidepressant agent such as trazodone, mirtazapine or agomelatine. A second approach is to start with a non-sedating antidepressant (e.g. the selective serotonin reuptake inhibitors, bupropion, venlafaxine or duloxetine); those with a persistent or treatment-emergent insomnia can be switched to a more sedating antidepressant, or offered a hypnotic or cognitive-behavioural therapy as adjunctive treatment. The review discusses the advantages and disadvantages of all treatment options, pharmacological and otherwise.

Influence of the novel antidepressant and melatonin agonist/serotonin2C receptor antagonist, agomelatine, on the rat sleep-wake cycle architecture

RATIONALE

The novel antidepressant, agomelatine, behaves as an agonist at melatonin MT(1) and MT(2) receptors and as an antagonist at serotonin (5-HT)(2C) receptors. In animal models and clinical trials, agomelatine displays antidepressant properties and re-synchronizes disrupted circadian rhythms.

OBJECTIVES

The objectives of this study were to compare the influence of agomelatine upon sleep-wake states to the selective melatonin agonists, melatonin and ramelteon, and to the selective 5-HT(2C) receptor antagonist, S32006.

METHODS

Rats were administered with vehicle, agomelatine, ramelteon, melatonin, or S32006, at the onset of either dark or light periods. Polygraphic recordings were performed and changes determined over 24 h, i.e., number and duration of sleep-wake episodes, latencies to rapid eye movement (REM) and slow-wave (SWS) sleep, power band spectra of the electroencephalogram (EEG), and circadian changes.

RESULTS

Administered at light phase onset, no changes were induced by agomelatine. In contrast, administered shortly before dark phase, agomelatine (10 and 40 mg/kg, per os) enhanced duration of REM and SWS sleep and decreased wake state for 3 h. Melatonin (10 mg/kg, per os) induced a transient enhancement in REM sleep followed by a reduction in REM and SWS sleep and an increase in waking. Ramelteon (10 mg/kg, per os) provoked a transient increase in REM sleep. Finally, S32006 (10 mg/kg, intraperitoneally), administered at dark phase onset, mimicked the increased SWS provoked by agomelatine, yet diminished REM sleep.

CONCLUSIONS

Agomelatine possesses a distinctive EEG profile compared with melatonin, ramelteon, and S32006, possibly reflecting co-joint agonist and antagonist properties at MT(1)/MT(2) and 5-HT(2C) receptors, respectively.