Differential Potency of Venlafaxine, Paroxetine, and Atomoxetine to Inhibit Serotonin and Norepinephrine Reuptake in Patients With Major Depressive Disorder

Association of inflammation cytokines with cognitive function in first-episode major depressive disorder

Objective

Abnormal cognitive functioning is a core symptom of Major Depressive Disorder (MDD) and is strongly correlated with MDD prognosis. Current studies suggest that the occurrence of MDD may be related to oxidative stress-induced inflammation, hypothalamic-pituitary-adrenal axis disorders, diminished monoamine function and microbe-brain-gut axis, among other pathways. In recent years, the relationship between the immune-inflammatory response and MDD has been a hot topic of research, but how the relationship between immunoinflammation and cognitive function is manifested in MDD is still unclear. In this study, we examined cognitive function characteristics, serum inflammatory factors, brain-derived neurotrophic factor, and their correlations before and after pharmacological treatment(paroxetine hydrochloride tablets) in patients with first-episode major depressive disorder, aiming to identify objective biomarkers for cognitive function assessment.

Methods

We included 22 patients with first-episode major depressive disorder and 27 healthy volunteers from the community during the same period. The Hamilton Depression Scale-17 (HAMD-17) assessed the severity of depressive symptoms at baseline and after 8 weeks of treatment. The Repeatable Battery for the Assessment of Neuropsychological Status(RBANS) evaluated cognitive function, and serum samples were collected to determine levels of inflammatory and neurotrophic factors at these two time points. For healthy volunteers, only HAMD-17 scale scores, RBANS scale scores, and serum samples were taken at baseline. Spearman's correlation analyzed the relationship between inflammatory factors, neurotrophic factors, and cognitive function. Multiple linear regression determined factors affecting cognitive function in first-time patients.

Results

Baseline findings indicated that patients' IL-6 and TNF-α levels exceeded those of healthy individuals, while their IFN-α levels were below; their scores in language, attention, delayed memory, and the RBANS scale were also lower than healthy counterparts. Post-treatment, patients' BDNF, IL-6, and TNF-α levels remained higher than those of healthy subjects, and their IFN-α levels were still lower; their language and attention scores were also inferior. Association analyses revealed an association between BDNF and visuospatial/constructional ability scores and language scores in patients with MDD at baseline, and a positive relationship between TNF-α and attention score. Multiple regression analysis indicated an association between TNF-α levels and attention scores in MDD patients at baseline.

Conclusions

Our study concludes that TNF-α and BDNF correlate with cognitive function in MDD at baseline, and furthermore, TNF-α could potentially serve as an objective biomarker to support the assessment of attentional function at baseline.

AMPA receptors modulate enhanced dopamine neuronal activity induced by the combined administration of venlafaxine and brexpiprazole

Addition of dopamine (DA)/serotonin (5-HT) partial agonists to 5-HT/norepinephrine (NE) reuptake inhibitors are commonly used to enhance the antidepressant response. The simultaneous inhibition of 5-HT and NE transporters with venlafaxine and its combination of brexpiprazole, which blocks the α2-adrenergic autoreceptor on NE terminals, could constitute a superior strategy. Anesthetized rats received venlafaxine and brexpiprazole for 2 and 14 days, then the firing activity of dorsal raphe nucleus 5-HT, locus coeruleus NE, and ventral tegmental area DA neurons were assessed. Net 5-HT and NE neurotransmissions were evaluated by assessing the tonic activation of 5-HT1A, and α1- and α2-adrenergic receptors in the hippocampus. The combination of brexpiprazole with venlafaxine resulted in normalized 5-HT and NE neuron activity, which occurred earlier than that with venlafaxine alone. A significant enhancement of the tonic activation of 5-HT1A receptors and α2-adrenoceptors in the hippocampus was observed following administration of the combination for 14 days. The combination more than doubled the number of DA neurons per electrode descent, after both 2 and 14 days, while this increase was observed only after 14 days of venlafaxine administration. This increase in population activity was prevented by NBQX, an AMPA receptor antagonist. In conclusion, early during administration, the combination of venlafaxine with brexpiprazole normalized firing activity of 5-HT and NE neurons, and increased the population activity of DA neurons through AMPA receptors. In the hippocampus, there was an overall increase in both 5-HT and NE transmissions. These results imply that this strategy could be a rapid-acting approach to treat depression.

Efficacy and dose-response relationships of antidepressants in the acute treatment of major depressive disorders: a systematic review and network meta-analysis

BACKGROUND

The optimal antidepressant dosages remain controversial. This study aimed to analyze the efficacy of antidepressants and characterize their dose-response relationships in the treatments of major depressive disorders (MDD).

METHODS

We searched multiple databases, including the Embase, Cochrane Central Register of Controlled Trials, PubMed, and Web of Science, for the studies that were conducted between January 8, 2016, and April 30, 2023. The studies are double-blinded, randomized controlled trials (RCTs) involving the adults (≥18 years) with MDD. The primary outcomes were efficacy of antidepressant and the dose-response relationships. A frequentist network meta-analysis was conducted, treating participants with various dosages of the same antidepressant as a single therapy. We also implemented the model-based meta-analysis (MBMA) using a Bayesian method to explore the dose-response relationships.

RESULTS

The network meta-analysis comprised 135,180 participants from 602 studies. All the antidepressants were more effective than the placebo; toludesvenlafaxine had the highest odds ratio (OR) of 4.52 (95% confidence interval [CI]: 2.65-7.72), and reboxetine had the lowest OR of 1.34 (95%CI: 1.14-1.57). Moreover, amitriptyline, clomipramine, and reboxetine showed a linear increase in effect size from low to high doses. The effect size of toludesvenlafaxine increased significantly up to 80 mg/day and subsequently maintained the maximal dose up to 160 mg/day while the predictive curves of nefazodone were fairly flat in different dosages.

CONCLUSIONS

Although most antidepressants were more efficacious than placebo in treating MDD, no consistent dose-response relationship between any antidepressants was observed. For most antidepressants, the maximum efficacy was achieved at lower or middle prescribed doses, rather than at the upper limit.

Venlafaxine's therapeutic reference range in the treatment of depression revised: a systematic review and meta-analysis

INTRODUCTION

The selective serotonin and norepinephrine reuptake inhibitor venlafaxine is among the most prescribed antidepressant drugs worldwide and, according to guidelines, its dose titration should be guided by drug-level monitoring of its active moiety (AM) which consists of venlafaxine (VEN) plus active metabolite O-desmethylvenlafaxine (ODV). This indication of therapeutic drug monitoring (TDM), however, assumes a clear concentration/effect relationship for a drug, which for VEN has not been systematically explored yet.

OBJECTIVES

We performed a systematic review and meta-analysis to investigate the relationship between blood levels, efficacy, and adverse reactions in order to suggest an optimal target concentration range for VEN oral formulations for the treatment of depression.

METHODS

Four databases (MEDLINE (PubMed), PsycINFO, Web of Science Core Collection, and Cochrane Library) were systematically searched in March 2022 for relevant articles according to a previously published protocol. Reviewers independently screened references and performed data extraction and critical appraisal.

RESULTS

High-quality randomized controlled trials investigating concentration/efficacy relationships and studies using a placebo lead-in phase were not found. Sixty-eight articles, consisting mostly of naturalistic TDM studies or small noncontrolled studies, met the eligibility criteria. Of them, five cohort studies reported a positive correlation between blood levels and antidepressant effects after VEN treatment. Our meta-analyses showed (i) higher AM and (ii) higher ODV concentrations in patients responding to VEN treatment when compared to non-responders (n = 360, k = 5). AM concentration-dependent occurrence of tremor was reported in one study. We found a linear relationship between daily dose and AM concentration within guideline recommended doses (75-225 mg/day). The population-based concentration ranges (25-75% interquartile) among 11 studies (n = 3200) using flexible dosing were (i) 225-450 ng/ml for the AM and (ii) 144-302 ng/ml for ODV. One PET study reported an occupancy of 80% serotonin transporters for ODV serum levels above 85 ng/ml. Based on our findings, we propose a therapeutic reference range for AM of 140-600 ng/ml.

CONCLUSION

VEN TDM within a range of 140 to 600 ng/ml (AM) will increase the probability of response in nonresponders. A titration within the proposed reference range is recommended in case of non-response at lower drug concentrations as a consequence of VEN's dual mechanism of action via combined serotonin and norepinephrine reuptake inhibition. Drug titration towards higher concentrations will, however, increase the risk for ADRs, in particular with supratherapeutic drug concentrations.

Moving from serotonin to serotonin-norepinephrine enhancement with increasing venlafaxine dose: clinical implications and strategies for a successful outcome in major depressive disorder

INTRODUCTION

Mental health disorders, especially depressive and anxiety disorders, are associated with substantial health-related burden. While the second-generation antidepressants are widely accepted as first-line pharmacological treatment for major depressive disorder (MDD), patient response to such treatment is variable, with more than half failing to achieve complete remission, and residual symptoms are frequently present.

AREAS COVERED

Here, the pharmacodynamics of venlafaxine XR are reviewed in relation to its role as both a selective serotonin reuptake inhibitor (SSRI) and a serotonin-norepinephrine-reuptake inhibitor (SNRI), and we look at how these pharmacodynamic properties can be harnessed to guide clinical practice, asking the question 'is it possible to develop a symptom-cluster-based approach to the treatment of MDD with comorbid anxiety utilizing venlafaxine XR?.' Additionally, three illustrative clinical cases provide practical examples of the utility of venlafaxine-XR in real-world clinical practice. The place of venlafaxine XR in managing fatigue/low energy, a frequent residual symptom in MDD, is explored using pooled data from clinical trials of venlafaxine XR.

EXPERT OPINION

Venlafaxine XR should be considered as a first-line treatment for MDD with or without comorbid anxiety, and there are clear pharmacodynamic signals supporting a symptom cluster-based treatment paradigm for venlafaxine XR.

Systematic review of studies using platelet serotonin content to assess bioeffect of serotonin reuptake inhibitors at the serotonin transporter

RATIONALE

Assessment of the bioeffect of serotonin reuptake inhibitors (SRIs, including both selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs)) at the serotonin transporter (SERT) in patients and healthy controls can have important theoretical and clinical implications.

OBJECTIVES

Bioeffect at SERT has been assessed by neuroimaging of brain SERT occupancy, through in vitro measurements of platelet serotonin (5-HT) uptake, and by measuring platelet 5-HT content pre- and post-initiation of SRI administration. Studies of platelet 5-HT content were reviewed in order to (1) determine the overall apparent bioeffect of SRIs; (2) compare bioeffect across types of SRIs; (3) compare the three approaches to assessing SRI bioeffect; and (4) determine how the findings might inform clinical practice.

METHODS

We performed a systematic review of the published studies that measured platelet 5-HT content to assess SRI bioeffect at the platelet SERT. Studies using neuroimaging and in vitro platelet 5-HT uptake to assess SRI bioeffect were reviewed for comparison purposes.

RESULTS

Clinical doses of SRIs typically resulted in 70-90% reductions in platelet 5-HT content. The observed bioeffect at the platelet SERT appeared similar among different SSRIs and SNRIs. The bioeffect estimations based on platelet 5-HT content were consistent with those obtained using neuroimaging to assess brain SERT occupancy and those based on the in vitro measurement of platelet 5-HT uptake.

CONCLUSIONS

In general, excellent agreement was seen in the apparent SRI bioeffect (70-90% inhibition) among the platelet 5-HT content studies and across the three bioeffect approaches. Theoretical and practical clinical implications are discussed.