Olanzapine/fluoxetine: a review of its use in patients with treatment-resistant major depressive disorder

Current emerging therapeutic targets and clinical investigational agents for schizophrenia: Challenges and opportunities

Since the first discovery of antipsychotics in the 1950s, targeting dopaminergic drugs has manifested to well manage the positive symptoms of schizophrenia with limited efficacy for the negative and cognitive symptoms. In past decades, extensive efforts have been undertaken towards the development of innovative agents that can effectively stabilize the dopamine and serotonin systems or target to nondopaminergic pathways, leading to various promising drug candidates entering into clinical trials. Notably, the sigma-2, 5-HT2A, and α1A receptor antagonist roluperidone, as well as a fixed-dose combination of the M1/4 receptor agonist KarXT, have been submitted for NDA applications. The dual agonist ulotaront, which targets TAAR1 and 5-HT1A receptors, and the GlyT1 inhibitor iclepertin have advanced into phase 3 clinical trials. Nevertheless, satisfactory therapeutic strategies for schizophrenia remain elusive. This review highlights current clinical endeavors in developing novel chemical small-molecule entities and fixed-dose combinations for the treatment of schizophrenia since 2017, thus facilitating the efficient development of the next generation of antipsychotics.

P-glycoprotein mediates the pharmacokinetic interaction of olanzapine with fluoxetine in rats

Clinical trials of olanzapine combined with fluoxetine (Olanzapine/Fluoxetine Combination, OFC) in the treatment of refractory depression have shown significant efficacy, but the drug-drug interaction (DDI) between them remains unclear. In this report, the pharmacokinetic interaction between olanzapine and fluoxetine was studied in wild-type (WT) and Mdr1a/b gene knockout (KO) rats. By analyzing the pharmacokinetics and tissue distribution of olanzapine in single dose and combination, the potential DDI mediated by P-gp was explored. The results showed that in WT rats, the combination of fluoxetine increased the peak concentration (Cmax, 44.1 ± 5.1 ng/mL in the combination group vs 9.0 ± 1.5 ng/mL in the monotherapy group) and the exposure (AUC0-t, 235.8 ± 22.7 h × ng/mL in the combination group vs 47.5 ± 8.4 h × ng/mL in monotherapy group) of olanzapine, and decreased the clearance (CL, 8119.0 ± 677.9 mL/h/kg in the combination group vs 49,469.0 ± 10,306.0 mL/h/kg in monotherapy group). At the same time, fluoxetine significantly increased the in vivo exposure of olanzapine in brain, liver, kidney and ileum of WT rats, indicating the occurrence of DDI. The same phenomenon was observed in Caco-2 cells in vitro as well. However, in KO rats, there was no significant difference in pharmacokinetic parameters between the monotherapy group and the combination group. In conclusion, P-gp plays an important role in the pharmacokinetic interaction between olanzapine and fluoxetine in rats. This study may provide a reference for the clinical safety of olanzapine combined with fluoxetine.

A New Paradigm for Achieving a Rapid Antidepressant Response

The substantive delay (often 4-6 weeks) between the commencement of an antidepressant and any discernible improvement in depressive symptoms is an ongoing concern in the management of depressive disorders. This delay incurs the risk of cessation of medication, self-harm/suicide and ongoing 'damage' to the brain caused by the illness. Both historically and now, off-label polypharmacy has been used in clinical practice in an attempt to facilitate both immediate- and long-term relief from symptoms. While somewhat effective, this strategy was unregulated and associated with severe adverse side effects for patients. In this article we proffer an alternative paradigm to achieve a more rapid antidepressant response by conceptualising the gap in terms of windows of response. The Windows of Antidepressant Response Paradigm (WARP) frames treatment response as windows of time in which a clinical response can be expected following initiation of an antidepressant. The paradigm defines three distinct windows-the immediate-response window (1-2 days), fast-response window (up to 1 week) and slow-response window (from 1 week onwards). Newer agents such as rapid-acting antidepressants are considered to act within the immediate-response window, whereas atypical antipsychotic augmentation strategies are captured within the fast-response window. The slow-response window represents the delay experienced with conventional antidepressant monotherapy. Novel agents such as esketamine and brexpiprazole are discussed as examples to better understand the clinical utility of WARP. This framework can be used to guide research in this field and aide the development of newer, more effective antidepressant agents as well as providing a strategy to guide the prescription of multiple agents in clinical practice.

Resveratrol ameliorates depressive disorder through the NETRIN1-mediated extracellular signal-regulated kinase/cAMP signal transduction pathway

Depressive disorder is a mental health disorder caused by the dysfunction of nerve regeneration, neuroendocrine and neurobiochemistry, which frequently results in cognitive impairments and disorder. Evidence has shown that resveratrol offers benefits for the treatment of depressive disorder. In the present study, the therapeutic effects of resveratrol were investigated and the potential mechanisms mediated by resveratrol were analyzed in hippocampal neuron cells. The anti‑oxidative stress and anti‑inflammatory properties of resveratrol were also examined in vitro and in vivo. The results revealed that resveratrol administration inhibited the inflammation in hippocampal neuron cells induced by ouabain. Oxidative stress in the hippocampal neuron cells was ameliorated by resveratrol treatment in vitro and in vivo. In addition, the apoptosis of hippocampal neuron cells was inhibited by the upregulation of anti‑apoptotic genes, including P53, B‑cell lymphoma‑2 (Bcl‑2) and Bcl‑2‑associated death promoter, and the downregulation of the cleaved caspase‑3 and caspase‑9. The analysis of the mechanism revealed that that resveratrol treatment suppressed the apoptosis of hippocampal neuron cells through the NETRIN1‑mediated extracellular signal‑regulated kinase/cAMP signal transduction pathway. The results of the in vivo assay showed that resveratrol treatment led to improvements in cognitive competence, learning memory ability and anxiety in a mouse model of depressive disorder induced by ouabain. In conclusion, these results indicated that resveratrol treatment had protective effects against oxidative stress and neuroinflammatory pathogenesis through the NETRIN1‑mediated extracellular signal‑regulated kinase/cAMP signal transduction pathway, suggesting that resveratrol treatment may be a potential antidepressant agent for the treatment of depressive disorder.

Melatonin Augments the Effects of Fluoxetine on Depression-Like Behavior and Hippocampal BDNF-TrkB Signaling

Depression is a debilitating psychiatric disorder with a huge socioeconomic burden, and its treatment relies on antidepressants including selective serotonin reuptake inhibitors (SSRIs). Recently, the melatonergic system that is closely associated with the serotonergic system has been implicated in the pathophysiology and treatment of depression. However, it remains unknown whether combined treatment with SSRI and melatonin has synergistic antidepressant effects. In this study, we applied a sub-chronic restraint stress paradigm, and evaluated the potential antidepressant effects of combined fluoxetine and melatonin in adult male mice. Sub-chronic restraint stress (6 h/day for 10 days) induced depression-like behavior as shown by deteriorated fur state, increased latency to groom in the splash test, and increased immobility time in the forced-swim test. Repeated administration of either fluoxetine or melatonin at 10 mg/kg during stress exposure failed to prevent depression-like phenotypes. However, combined treatment with fluoxetine and melatonin at the selected dose attenuated stress-induced behavioral abnormalities. Moreover, we found that the antidepressant effects of combined treatment were associated with the normalization of brain-derived neurotrophic factor (BDNF)-tropomyosin receptor kinase B (TrkB) signaling in the hippocampus, but not in the prefrontal cortex. Our findings suggest that combined fluoxetine and melatonin treatment exerts synergistic antidepressant effects possibly by restoring hippocampal BDNF-TrkB signaling.

Aripiprazole: from pharmacological profile to clinical use

Clinical experience with aripiprazole has confirmed the effectiveness and the safety of this novel antipsychotic drug in patients with schizophrenia as well as for the treatment of mania in type I bipolar disorder. However the generalization of the results from clinical trials requires further effort in order to address some issues and to overcome incorrect and partial interpretation of the clinical evidence. This article provides some straightforward guidance that may help clinical psychiatrists to translate the mechanism of action of aripiprazole into clinical setting, thus improving the appropriate use of the drug through rational application of its pharmacological profile. Examples of paradigmatic clinical situations are presented and discussed, suggesting possible intervention strategies, which may contribute to achieving the most appropriate use of the pharmacological properties of aripiprazole in real life settings.

Faster, better, stronger: towards new antidepressant therapeutic strategies

Major depression is a highly prevalent disorder and is predicted to be the second leading cause of disease burden by 2020. Although many antidepressant drugs are currently available, they are far from optimal. Approximately 50% of patients do not respond to initial first line antidepressant treatment, while approximately one third fail to achieve remission following several pharmacological interventions. Furthermore, several weeks or months of treatment are often required before clinical improvement, if any, is reported. Moreover, most of the commonly used antidepressants have been primarily designed to increase synaptic availability of serotonin and/or noradrenaline and although they are of therapeutic benefit to many patients, it is clear that other therapeutic targets are required if we are going to improve the response and remission rates. It is clear that more effective, rapid-acting antidepressants with novel mechanisms of action are required. The purpose of this review is to outline the current strategies that are being taken in both preclinical and clinical settings for identifying superior antidepressant drugs. The realisation that ketamine has rapid antidepressant-like effects in treatment resistant patients has reenergised the field. Further, developing an understanding of the mechanisms underlying the rapid antidepressant effects in treatment-resistant patients by drugs such as ketamine may uncover novel therapeutic targets that can be exploited to meet the Olympian challenge of developing faster, better and stronger antidepressant drugs.

Effects of chronic electroacupuncture on depression- and anxiety-like behaviors in rats with chronic neuropathic pain

Growing evidence indicates that chronic neuropathic pain is frequently accompanied by an array of psychiatric diseases, such as depression and anxiety. Electroacupuncture (EA), as one therapy of traditional Chinese medicine, has displayed potent antidepressant-like effects in numerous clinical studies. The present study was designed to examine the possible effects of EA on the depressive and anxiety disorders induced by neuropathic pain. A classic rat model of neuropathic pain was produced by chronic constriction injury (CCI) of the sciatic nerve. EA was performed on acupoints “Bai-Hui” (GV20) and unilateral “Yang-Ling-Quan” (GB34). The antidepressive and anxiolytic effects of EA treatment were analyzed using the forced swimming test (FST) and the elevated plus maze (EPM) test, respectively. CCI resulted in remarkable depression- and anxiety-like behaviors, whereas the chronic EA treatment significantly improved the behavioral deficits of CCI rats. Moreover, the phosphorylation level of the NMDA receptor type 1 (NR1) subunit was decreased in the hippocampus of CCI rats. Intriguingly, continuous EA treatment effectively blocked this decrease in the levels of pNR1. These results suggested that EA has antidepressive and anxiolytic effects on rats with neuropathic pain and that this might be associated with restoring the phosphorylation of NR1 in the hippocampus.

Neural response to emotional stimuli associated with successful antidepressant treatment and behavioral activation

BACKGROUND

Major Depressive Disorder (MDD) is a leading cause of disability globally. Currently available treatments have limited efficacy and combination strategies are frequently used. Several lines of research have demonstrated that MDD patients experience impairments in various components of affective processing, including regulation of affective states.

AIM

To identify baseline and 1-week neuroimaging predictors of response to a 6-week trial of fluoxetine/olanzapine combination treatment during an affective processing task.

METHODS

Twenty-one MDD patients and 18 healthy controls were enrolled in the study. MDD patients were treated for 6 weeks with fluoxetine (40-60 mg/day) and olanzapine (5-12.5mg/day). All participants viewed images from the International Affective Picture Rating System during a functional magnetic resonance (fMRI) scan at baseline and 1 week.

RESULTS

There was a 57% response rate (defined as a 50% decrease in Hamilton Rating Scale for Depression-17 item) at 6 weeks. At baseline, responders had increased premotor activity while viewing negative images compared to non-responders and healthy controls. Higher baseline premotor activity was also predictive of greater percent change on the HAMD-17 and improvement in negative disposition and behavioral drive. Non-responders exhibited increased insular activity at baseline compared to responders. Higher activity in the posterior cingulate cortex was also predictive of greater percent change on the HAMD-17. Change from baseline to 1 week did not produce any significant predictive findings.

CONCLUSIONS

Treatment with fluoxetine/olanzapine demonstrated similar biomarkers of response to monotherapeutic strategies. In particular, posterior cingulate cortex, anterior insula, and premotor cortex may show predictive differences in their response to affective images prior to treatment. Further research needs to be conducted to determine the utility of early changes in emotion circuitry in predicting antidepressant response.

Clinical issues in use of atypical antipsychotics for depressed patients

Major depressive disorder (MDD) is a chronic, recurrent mental disease that causes serious disability. Because currently available antidepressants have limited efficacy with respect to response and remission in patients with MDD, clinicians must choose the best available treatment interventions for patients who do not respond to initial antidepressant treatment. The existing literature demonstrates that augmentation with atypical antipsychotics (AAs) shows higher response and remission rates compared with antidepressant monotherapy, but is associated with more withdrawals due to adverse events. In this paper, specific clinical issues in the use of AA augmentation for patients with MDD are briefly discussed. Given the limited information and clinical knowledge on the proper and effective use of AAs for MDD, future research should focus on practical clinical issues that can be commonly seen in routine practice but have not been addressed yet. This is because the use of AAs is likely to expand as there is good evidence for their effectiveness and tolerability as augmentation therapy for patients with MDD.

Pharmacokinetic evaluation of olanzapine + fluoxetine for the treatment of bipolar depression

INTRODUCTION

A proprietary combination of the atypical antipsychotic drug olanzapine and the serotonin reuptake inhibitor fluoxetine (OFC, Symbyax) was approved for the treatment of bipolar depression based on a double-blind, placebo-controlled comparison of olanzapine, OFC, and placebo.

AREAS COVERED

This review considers published controlled and uncontrolled studies of the efficacy, pharmacodynamics, pharmacokinetics, interactions, and adverse effects of OFC. Beyond previously reviewed efficacy studies, an open-label 7-week study of 161 bipolar depressed patients (93% bipolar I), and an 8-week double-blind study of 833 bipolar I depressed patients with an open-label extension were identified. The structure and limitations of clinical trials of OFC are critically addressed.

EXPERT OPINION

OFC trades simplicity of administration for loss of flexibility of dosing and lack of a generic preparation, both of which are available for olanzapine and fluoxetine separately. Clinical trials are limited by short-term follow-up, exclusive use of symptom rating scale scores, limitation of subjects to those with depression that is not overly complex or comorbid, lack of consideration of subsyndromal hypomania and mood cycling, and high dropout rates. In the absence of comparisons to mood stabilizers combined with each other and/or antidepressants, the role of OFC in the treatment of bipolar depression remains unclear.

The effects of combining serotonin reuptake inhibition and 5-HT7 receptor blockade on circadian rhythm regulation in rodents

Disruption of circadian rhythms may lead to mood disorders. The present study investigated the potential therapeutic utility of combining a 5-HT7 antagonist with a selective serotonin (5-HT) reuptake inhibitor (SSRI), the standard of care in depression, on circadian rhythm regulation. In tissue explants of the suprachiasmatic nucleus (SCN) from PER2::LUC mice genetically modified to report changes in the expression of a key clock protein, the period length of PER2 bioluminescence was shortened in the presence of AS19, a 5-HT7 partial agonist. This reduction was blocked by SB269970, a selective 5-HT7 antagonist. The SSRI, escitalopram, had no effect alone on period length, but a combination with SB269970, yielded significant increases. Dosed in vivo, escitalopram had little impact on the occurrence of activity onsets in rats given access to running wheels, whether the drug was given acutely or sub-chronically. However, preceding the escitalopram treatment with a single acute dose of SB269970 produced robust phase delays, in keeping with the in vitro explant data. Taken together, these findings suggest that the combination of an SSRI and a 5-HT7 receptor antagonist has a greater impact on circadian rhythms than that observed with either agent alone, and that such a multimodal approach may be of therapeutic value in treating patients with poor clock function.

Meta-review of depressive subtyping models

BACKGROUND

Increasing dissatisfaction with the non-specificity of major depression has led many to propose more specific depressive subtyping models. The present meta-review seeks to map dominant depressive subtype models, and highlight definitions and overlaps.

METHODS

A database search in Medline and EMBASE of proposed depressive subtypes, and limited to reviews published between 2000 and 2011, was undertaken. Of the more than four thousand reviews, 754 were judged as potentially relevant and provided the base for the present selective meta-review.

RESULTS

Fifteen subtype models were identified. The subtypes could be divided into five molar categories of (1) symptom-based subtypes, such as melancholia, psychotic depression, atypical depression and anxious depression, (2) aetiologically-based subtypes, exemplified by adjustment disorders, early trauma depression, reproductive depression, perinatal depression, organic depression and drug-induced depression, (3) time of onset-based subtypes, as illustrated by early and late onset depression, as well as seasonal affective disorder, (4) gender-based (e.g. female) depression, and (5) treatment resistant depression. An overview considering definition, bio-psycho-social correlates and the evidence base of treatment options for each subtype is provided.

LIMITATIONS

Despite the large data base, this meta-review is nevertheless narrative focused.

CONCLUSIONS

Subtyping depression is a promising attempt to overcome the non-specificity of many diagnostic constructs such as major depression, both in relation to their intrinsic non-specificity and failure to provide treatment-specific information. If a subtyping model is to be advanced it would need, however, to demonstrate differential impacts of causes and treatments.

General and comparative efficacy and effectiveness of antidepressants in the acute treatment of depressive disorders: a report by the WPA section of pharmacopsychiatry

Current gold standard approaches to the treatment of depression include pharmacotherapeutic and psychotherapeutic interventions with social support. Due to current controversies concerning the efficacy of antidepressants in randomized controlled trials, the generalizability of study findings to wider clinical practice and the increasing importance of socioeconomic considerations, it seems timely to address the uncertainty of concerned patients and relatives, and their treating psychiatrists and general practitioners. We therefore discuss both the efficacy and clinical effectiveness of antidepressants in the treatment of depressive disorders. We explain and clarify useful measures for assessing clinically meaningful antidepressant treatment effects and the types of studies that are useful for addressing uncertainties. This includes considerations of methodological issues in randomized controlled studies, meta-analyses, and effectiveness studies. Furthermore, we summarize the differential efficacy and effectiveness of antidepressants with distinct pharmacodynamic properties, and differences between studies using antidepressants and/or psychotherapy. We also address the differential effectiveness of antidepressant drugs with differing modes of action and in varying subtypes of depressive disorder. After highlighting the clinical usefulness of treatment algorithms and the divergent biological, psychological, and clinical efforts to predict the effectiveness of antidepressant treatments, we conclude that the spectrum of different antidepressant treatments has broadened over the last few decades. The efficacy and clinical effectiveness of antidepressants is statistically significant, clinically relevant, and proven repeatedly. Further optimization of treatment can be helped by clearly structured treatment algorithms and the implementation of psychotherapeutic interventions. Modern individualized antidepressant treatment is in most cases a well-tolerated and efficacious approach to minimize the negative impact of otherwise potentially devastating and life-threatening outcomes in depressive disorders.

Treatment strategies for dosing the second generation antipsychotics

BACKGROUND

The second generation antipsychotics now have clinical approvals for the treatment of schizophrenia, bipolar depression, bipolar mania, autism, major depressive disorder and are used furthermore off-label to treat other mental disorders. Each agent is unique in its pharmacodynamic profile and allows for unique dosing strategies to be employed when treating these different disorders.

AIMS

To review relevant data regarding the second generation antipsychotics and their empirical dosing strategies. To further review and comment theoretically in these areas where substantial, definitive data are lacking.

MATERIALS AND METHODS

A MEDLINE and recent textbook review was conducted regarding each second generation antipsychotic and cross-referenced with searches for major mental disorders. The findings are compiled in the review below.

DISCUSSION

The second generation antipsychotics are clearly delineated in the treatment of psychosis and mania and share similar mechanisms of action to achieve these results: dopamine-2 receptor antagonism for efficacy and serotonin-2a receptor antagonism for EPS tolerability. From here, each agent has a unique pharmacodynamic and pharmacokinetic profile where some agents carry more, or less antidepressant, anxiolyic, or hypnotic profiles. Choosing an agent, and dosing it in low, middle, or high ranges may result in differential effectiveness and tolerability.

CONCLUSION

The second generation antipsychotics have many clinical applications in psychiatric practice. This article serves to review this and also suggests ways clinicians may optimize treatment based upon patient diagnosis and utilizing appropriate dosing of each individual second generation antipsychotic.

Aripiprazole as adjunctive therapy for patients with major depressive disorder: overview and implications of clinical trial data

Aripiprazole was initially approved to treat schizophrenia and later approved for bipolar mania, as a monotherapy and an adjunctive therapy (manic or mixed episodes), and for irritability associated with autism. Aripiprazole is a partial agonist at dopamine D(2) and D(3) and serotonin 5-HT(1A) receptors, and is an antagonist at 5-HT(2A) receptors. This profile, and convincing preliminary data from small-scale studies, provided the rationale for the large-scale exploration of aripiprazole for unipolar depression. Recently, three 6-week, large-scale, randomized, double-blind, placebo-controlled clinical trials demonstrated clinically meaningful efficacy for aripiprazole as an adjunctive therapy to antidepressants for treating major depressive disorder (MDD). In November 2007, aripiprazole was approved by the US FDA as an adjunctive therapy to antidepressants for treating MDD, with support from two of the above-mentioned trials. In the trials, aripiprazole was demonstrated to be safe and well tolerated, and showed a minimal trend for weight gain over the course of a 6-week treatment. The incidence of akathisia was higher than that reported in studies of patients with schizophrenia; however, most cases were mild to moderate and infrequently lead to discontinuation (5/1090 from all three trials). This comprehensive review provides an overview of the data from all three 6-week studies (including a pooled analysis) and from an unpublished 52-week, open-label extension study, to inform physicians and facilitate reasonable treatment decisions. In addition, specific issues associated with the use of aripiprazole as an adjunctive therapy in patients with MDD, including possible early treatment effect, appropriate timing of therapy initiation, appropriate dosing and duration of treatment, possible differential effect on depressive subgroups and long-term tolerability, are also discussed.