Pindolol augmentation enhances response outcomes in first depressive episodes

Recent Developments in Pharmacotherapy of Depression: Bench to Bedside

For the last 70 years, we did not move beyond the monoamine hypothesis of depression until the approval of the S-enantiomer of ketamine, an N-methyl-D-aspartate (NMDA) receptor blocker and the first non-monoaminergic antidepressant characterized by rapid antidepressant and antisuicidal effects. A similar profile has been reported with another NMDA receptor antagonist, dextromethorphan, which has also been approved to manage depression in combination with bupropion. More recently, the approval of a positive allosteric modulator of GABA-A receptors, brexanolone, has added to the list of recent breakthroughs with the relatively rapid onset of antidepressant efficacy. However, multiple factors have compromised the clinical utility of these exciting discoveries in the general population, including high drug acquisition costs, mandatory monitoring requirements, parenteral drug administration, lack of insurance coverage, indirect COVID-19 effects on healthcare systems, and training gaps in psychopharmacology. This narrative review aims to analyze the clinical pharmacology of recently approved antidepressants and discuss potential barriers to the bench-to-bedside transfer of knowledge and clinical application of exciting recent discoveries. Overall, clinically meaningful advances in the treatment of depression have not reached a large proportion of depressed patients, including those with treatment-resistant depression, who might benefit the most from the novel antidepressants.

Neglected but not negligible aspects of antidepressants and their availability in bipolar depression

OBJECTIVES

Although many antidepressants are available, they are not always used appropriately. For appropriate use of antidepressants, the old concept of a linear dose-response relationship, in which the dose is linearly increased to achieve a sufficient antidepressant effect, should be reconsidered. Furthermore, there is ongoing debate on the safe and appropriate use of antidepressants in patients with bipolar depression. Antidepressants may be used under certain conditions in patients with bipolar depression. These neglected-but not negligible-aspects of antidepressants have been discussed herein.

METHODS

A narrative qualitative review RESULTS: Dose-response relationships of antidepressants such as selective serotonin reuptake inhibitors (SSRIs) are not linear. They may be bell-shaped, with efficacy initially increasing with an increase in dose but decreasing when the dose is increased beyond a certain point. Despite using international diagnostic criteria, uncertainty remains on whether operationally diagnosed depression is latent bipolar I depression, latent bipolar II depression, or true depression. Furthermore, operationally diagnosed bipolar II depression may be latent bipolar I depression, true bipolar II depression, or depression with false hypomanic episodes. Manic/hypomanic switches are most likely to occur in patients receiving tricyclic antidepressants, followed by those receiving serotonin and noradrenaline reuptake inhibitors and SSRIs, in that order. Also, these switches are most likely to occur in patients with bipolar I depression, followed by those with bipolar II depression and true depression, in that order.

CONCLUSIONS

Considering the diagnostic subtype of bipolar depression and antidepressant properties may help to determine the optimal treatment strategy.

Is the bell-shaped dose-response curve of the selective serotonin reuptake inhibitor due to 5-HT1A auto-receptors?

A dose-response curve is a plot of drug efficacy versus dose. Interestingly, some antidepressants show a bell-shaped dose-response curve where increasing dose leads to increasing efficacy only up to a point, whereupon further increases lead to decreasing efficacy. Here, we propose that the first part of the curve reflects the basic, uncomplicated dose-response relationship of these antidepressants whereas the second, decreasing part remains to be explained. Our hypothesis is that a negative feedback pathway through 5-HT1A auto-receptors decreases the efficacy of selective serotonin reuptake inhibitors with increasing dose, thereby creating the second, anomalous part of the dose-response curve. This effect can also account for the so-called therapeutic window of such antidepressants.

Overcoming Resistance to Selective Serotonin Reuptake Inhibitors: Targeting Serotonin, Serotonin-1A Receptors and Adult Neuroplasticity

Major depressive disorder (MDD) is the most prevalent mental illness contributing to global disease burden. Selective serotonin (5-HT) reuptake inhibitors (SSRIs) are the first-line treatment for MDD, but are only fully effective in 30% of patients and require weeks before improvement may be seen. About 30% of SSRI-resistant patients may respond to augmentation or switching to another antidepressant, often selected by trial and error. Hence a better understanding of the causes of SSRI resistance is needed to provide models for optimizing treatment. Since SSRIs enhance 5-HT, in this review we discuss new findings on the circuitry, development and function of the 5-HT system in modulating behavior, and on how 5-HT neuronal activity is regulated. We focus on the 5-HT1A autoreceptor, which controls 5-HT activity, and the 5-HT1A heteroreceptor that mediates 5-HT actions. A series of mice models now implicate increased levels of 5-HT1A autoreceptors in SSRI resistance, and the requirement of hippocampal 5-HT1A heteroreceptor for neurogenic and behavioral response to SSRIs. We also present clinical data that show promise for identifying biomarkers of 5-HT activity, 5-HT1A regulation and regional changes in brain activity in MDD patients that may provide biomarkers for tailored interventions to overcome or bypass resistance to SSRI treatment. We identify a series of potential strategies including inhibiting 5-HT auto-inhibition, stimulating 5-HT1A heteroreceptors, other monoamine systems, or cortical stimulation to overcome SSRI resistance.

Regional default mode network connectivity in major depressive disorder: modulation by acute intravenous citalopram

The relationship between altered default mode network (DMN) connectivity and abnormal serotonin function in major depressive disorder (MDD) has not been investigated. Using intravenous citalopram and resting-state fMRI, we investigated DMN intra-network connectivity and serotonin function in 77 healthy controls and patients with MDD. There were no significant main effects of MDD or citalopram on DMN intra-network connectivity; however, significant interactions indicated that group differences under saline were modified by citalopram. In MDD patients during saline infusion, in contrast with controls, the DMN (i) did not include the precuneus that was instead part of an anti-correlated network but (ii) did include amygdala that was part of the anti-correlated network in controls. Citalopram infusion in MDD patients restored the pattern seen in controls under saline. In healthy controls, citalopram infusion disengaged the precuneus from the DMN and engaged the amygdala, partially reproducing the abnormalities seen under saline in MDD. In exploratory analyses within the MDD group, greater rumination self-ratings were associated with greater intra-network connectivity of the anterior cingulate cortex with the DMN. We hypothesise that, in MDD, disengagement of the precuneus from the DMN relates to overgeneral memory bias in rumination. The opposite effect, with greater engagement of the amygdala in the DMN, reflects the negative valence of rumination. Reversal of these abnormalities by citalopram suggests that they may be related to impaired serotonin function. That citalopram engaged the amygdala in the DMN in controls may relate to the paradoxical effects on aversive processing seen with acute SSRIs in healthy subjects.

YL-0919, a dual 5-HT1A partial agonist and SSRI, produces antidepressant- and anxiolytic-like effects in rats subjected to chronic unpredictable stress

YL-0919 has been identified as a novel dual 5-HT_1A partial agonist and serotonin reuptake inhibitor. In the current study, we demonstrated that YL-0919 produced prominent antidepressant-like and anxiolytic-like effects in a chronic unpredictable stress (CUS) rat model. Male SD rats were exposed to CUS for 5 weeks; YL-0919 (1.25 and 2.5 mg/kg) or a positive control fluoxetine (Flx, 10 mg/kg) was orally administered daily. YL-0919 or Flx treatment significantly increased the sucrose preference rate, the locomotor activity in an open field test (OFT), the latency to feed in a novelty-suppressed feeding test (NSFT), and both the percentage of time spent in the open arms and the number of entries into the open arms in an elevated plus-maze test. YL-0919 or Flx treatment significantly suppressed the serum levels of ACTH and corticosterone in CUS-exposed rats. Additionally, YL-0919 or Flx treatment significantly enhanced the levels of cAMP, the expression of phosphorylated cAMP response element-binding protein (pCREB) and brain-derived neurotrophic factor (BDNF) in the hippocampus of CUS-exposed rats. Similar to Flx, YL-0919 treatment significantly enhanced the dendritic complexity, and increased the number of dendritic nodes as well as the spine length and number of branch nodes in the hippocampal pyramidal neurons of CUS-exposed rats. Overall, our results reveal that YL-0919 suppresses the HPA axis and exerts antidepressant-like and anxiolytic-like effects in CUS-exposed rats, which are associated with the enhanced cAMP signaling and hippocampal dendritic complexity.

Is pindolol augmentation effective in depressed patients resistant to selective serotonin reuptake inhibitors? A systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis was conducted to assess the use of pindolol augmentation in depressed patients resistant to selective serotonin reuptake inhibitor (SSRI) therapy.

METHODS

A comprehensive search of PubMed, Cochrane, Embase, Web of Science, and PsychINFO databases from 1970 through December 2013 was conducted. Only randomized controlled trials (RCTs) studied on unipolar SSRI-resistant depressed adults were included. The primary outcome was mean change scores of depressive symptom on the depression rating scales, assessed with standardized mean differences.

RESULTS

Five RCTs consisting of 154 patients met all inclusion and exclusion criteria. The overall pooled effect size in the primary and secondary efficacy analysis showed no significant effects of pindolol plus SSRI therapy (standardized mean difference = -0.43, p = 0.24; OR = 1.92, p = 0.39, respectively). In terms of acceptability, there was no statistical difference in either tolerability or safety between the two groups (OR = 0.46, p = 0.40; OR = 0.90, p = 0.94, respectively). These estimates remained robust through several sensitivity and subgroup analyses, except 7.5 mg-qd pindolol augmentation did show a significant benefit over 2.5-mg tid pindolol augmentation.

CONCLUSIONS

Pindolol augmentation may not be suitable for treatment-resistant depression patients with SSRI-resistant depression. However, once-daily high-dose pindolol (7.5 mg qd) appears to show a promising benefit in these patients.

Developments in the field of antidepressants, where do we go now?

Major depression is a severe psychiatric syndrome with very high prevalence and socio-economic impact. Its pathophysiology is poorly known, yet several neurotransmitter systems and brain areas have been implicated. Selective serotonin (5-hydroxytryptamine, 5-HT) reuptake inhibitors (SSRI) and serotonin and norepinephrine reuptake inhibitors (SNRI) are most used antidepressant treatments. However, these drugs show slow onset of action and limited efficacy, making necessary the use of drug augmentation strategies or more aggressive interventions. Two important observations have emerged in recent years indicating that more rapid and effective antidepressant treatments are possible. Hence, the deep brain stimulation (DBS) of ventral anterior (subgenual) cingulate cortex (Cg25) evokes rapid mood improvements in subgroups of treatment-resistant depressive patients, likely mediated by a functional remodelling of cortico-limbic circuits. On the other hand, the non-competitive NDMA receptor antagonist ketamine can also evoke rapid (e.g., 2h) and persistent (up to 1 wk) improvements in some treatment-resistant patients. Moreover, recent preclinical observations indicate the antidepressant capacity of mGluR agents. Overall, this supports the usefulness of glutamatergic transmission as a new area in antidepressant drug development. On the monoamine side, new preclinical and clinical research should clarify the different roles played by 5-HT receptors in depression as well as the brain areas and circuits responsible for therapeutic improvement. This will lead to the synthesis of new agents blocking the serotonin (and possibly norepinephrine) transporter which will also activate or block 5-HT receptors playing respectively positive (e.g., postsynaptic 5-HT1A, 5-HT4) or negative (e.g., presynaptic 5-HT1A,/1B, 5-HT2A, 5-HT2C,5-HT3, etc.) roles in antidepressant effects.

The role of 5-HT1A receptors in mediating acute negative effects of antidepressants: implications in pediatric depression

Acute antidepressant exposure elevates the frequency of impulsive behavior and suicidal thoughts in children and adolescents with major depressive disorder (MDD). Long-term antidepressant treatment, however, is beneficial for pediatric MDD, so it is necessary to explore novel treatments that prevent the potentially dangerous consequences of acute antidepressant initiation. In the present study, a treatment strategy designed to reverse the acute negative behavioral effects of antidepressants was tested in rodents. Co-administration of the 5-HT1A receptor (5-HT1AR) antagonist WAY-100635 reversed the negative effects of acute fluoxetine, a serotonin reuptake inhibitor, but not reboxetine, a norepinephrine reuptake inhibitor, supporting the involvement of 5-HT1AR in mediating the negative consequences of acute selective serotonin reuptake inhibitor (SSRI) treatment. No 5-HT1AR antagonists are currently approved for use in pediatric populations, so alternative strategies should be explored. One such strategy was suggested based on the hypothesis that the rate of 5-HT1AR activation and the subsequent inhibition of serotonergic neuron activity caused by acute SSRI administration is proportional to the loading rate of an antidepressant. Existing pharmacological data were examined, and significant correlations were observed between the half-life of antidepressants and the rate of suicide-related events (SREs). Specifically, antidepressants with longer half-lives have lower rates of SREs. On the basis of these data, novel dosing strategies were developed for five antidepressants to mimic the pharmacological profile of the antidepressant with the longest half-life, fluoxetine. These dosing strategies could be used to decrease the rate of SREs associated with acute antidepressant treatment in pediatric MDD until an improved pharmacological treatment is developed.

A review of vilazodone, serotonin, and major depressive disorder

Objective: To review the mechanism of selective serotonin reuptake inhibitor (SSRI)–mediated serotonergic neurotransmission, focusing on serotonin 1A (5-HT_1A) autoreceptors, which are proposed to be involved in delaying therapeutic efficacy. Vilazodone was specifically designed to function both as an SSRI and a partial agonist at 5-HT_1A receptors. This combined mechanism is proposed to decrease time to efficacy, minimize sexual side effects, and provide concomitant anxiolytic properties.

Data Sources: A PubMed search of all English-language articles from January 1990 to January 2013 was conducted using the search terms depression and 5-HT_1A, depression and buspirone, depression and pindolol, and vilazodone.

Study Selection: We found 47 articles and abstracts that were selected for inclusion on the basis of information about the pharmacology of 5-HT_1A receptors and the clinical data on pindolol, buspirone, and vilazodone in depression.

Data Extraction: This review summarizes current literature involving antidepressant activity, the role of 5-HT_1A autoreceptors, and clinical trials involving serotonin reuptake inhibition in conjunction with 5-HT_1A agonists and partial agonists, with a focus on vilazodone.

Results:Vilazodone has demonstrated efficacy in 2 large, randomized, double-blind, placebo-controlled trials in major depressive disorder. Results suggest that vilazodone has a low incidence of sexual side effects and is effective in patients with high levels of anxiety. A pooled analysis shows evidence of significant symptom reduction after only 1 week of therapy.

Conclusions: If future studies corroborate the clinical benefits attributed to its mechanism of action, vilazodone may show potential advantages in terms of onset of action, sexual side effects, and anxiolytic activity in patients with major depressive disorder.

Antidepressant-like activity of YL-0919: a novel combined selective serotonin reuptake inhibitor and 5-HT1A receptor agonist

It has been suggested that drugs combining activities of selective serotonin reuptake inhibitor and 5-HT1A receptor agonist may form a novel strategy for higher therapeutic efficacy of antidepressant. The present study aimed to examine the pharmacology of YL-0919, a novel synthetic compound with combined high affinity and selectivity for serotonin transporter and 5-HT1A receptors. We performed in vitro binding and function assays and in vivo behavioral tests to assess the pharmacological properties and antidepressant-like efficacy of YL-0919. YL-0919 displayed high affinity in vitro to both 5-HT1A receptor and 5-HT transporter prepared from rat cortical tissue. It exerted an inhibitory effect on forskolin-stimulated cAMP formation and potently inhibited 5-HT uptake in both rat cortical synaptosomes and recombinant cells. After acute p.o. administration, very low doses of YL-0919 reduced the immobility time in tail suspension test and forced swimming test in mice and rats, with no significant effect on locomotor activity in open field test. Furthermore, WAY-100635 (a selective 5-HT1A receptor antagonist, 0.3 mg/kg) significantly blocked the effect of YL-0919 in tail suspension test and forced swimming test. In addition, chronic YL-0919 treatment significantly reversed the depressive-like behaviors in chronically stressed rats. These findings suggest that YL-0919, a novel structure compound, exerts dual effect on the serotonergic system, as both 5-HT1A receptor agonist and 5-HT uptake blocker, showing remarkable antidepressant effects in animal models. Therefore, YL-0919 may be used as a new option for the treatment of major depressive disorder.

Pooled analysis of sustained response rates for extended release quetiapine fumarate as monotherapy or adjunct to antidepressant therapy in patients with major depressive disorder

BACKGROUND

Clinical trials are not generally powered to analyze outcomes such as sustained response. We evaluated sustained response rates for patients with major depressive disorder receiving quetiapine XR as monotherapy or adjunct therapy.

METHOD

Post hoc analyses of pooled data from four previously reported randomized, placebo-controlled studies of quetiapine XR 150 and 300 mg/day as monotherapy or adjunct therapy to ongoing antidepressant. Sustained response rates (≥50% reduction in MADRS total score at specific timepoint and each subsequent visit until Week 6) were calculated at Weeks 1, 2, and 4; rates were compared using a Cochran-Mantel-Haenszel analysis.

RESULTS

In the monotherapy studies, the proportion of patients experiencing sustained response was greater with quetiapine XR 150 mg/day versus placebo at Week 2 (20.0% vs. 13.3%; p<0.05) and Week 4 (33.3% vs. 23.3%; p<0.01) (observed cases [OC]). The corresponding sustained response rates for quetiapine XR 300 mg/day were 18.0% (p=0.104) and 29.7% (p=0.063), respectively (OC). The proportion of patients experiencing sustained response was greater in the adjunct studies versus placebo at Weeks 2 and 4 for quetiapine XR 150 (Week 2, 30.1% vs. 15.2%, p<0.001; Week 4, 40.1% vs. 32.0%, p<0.05) and 300 mg/day (Week 2, 29.0% vs. 15.2%, p<0.001; Week 4, 42.0% vs. 32.0%, p<0.05) (OC).

LIMITATIONS

Post hoc analyses, acute treatment period; no active comparator.

CONCLUSIONS

Quetiapine XR as monotherapy (150 mg/day at Weeks 2 and 4) or adjunct to ongoing antidepressant therapy (150 and 300 mg/day at Weeks 2 and 4) increased sustained response rates versus placebo.

Involvement of serotonin 5-HT3 receptors in the modulation of noradrenergic transmission by serotonin reuptake inhibitors: a microdialysis study in rat brain

RATIONALE

Selective serotonin reuptake inhibitors (SSRIs), in addition to being able to enhance serotonergic neurotransmission, are able to modulate other brain systems involved in depression.

OBJECTIVES

This study evaluates the neurochemical effect of the SSRI citalopram on brain noradrenergic activity and the serotonin receptor involved in this effect.

METHODS

Dual-probe microdialysis in the locus coeruleus (LC) and prefrontal cortex (PFC) was performed in freely awake rats.

RESULTS

Systemic citalopram (10 mg/kg, i.p.) increased noradrenaline (NA) in the LC (E max = 141 ± 13%) and simultaneously decreased NA in the PFC (Emax = -46 ± 7%). In the local presence into the LC of the α2-adrenoceptor antagonist RS79948 (1 μM), systemic citalopram increased NA in the LC (Emax = 157 ± 25%) and PFC (Emax = 175 ± 24%). Local citalopram (0.1-100 μM) into the LC induced NA increase in the LC (Emax = 210 ± 25%) and decrease in the PFC (Emax = -38 ± 9%). Local LC citalopram effect was abolished by LC presence of the 5-HT3 receptor antagonist MDL72222 (1 μM) but not the 5-HT1/2 receptor antagonist methiothepin (1 μM). Systemic citalopram in the LC presence of MDL72222 did not modify NA in the LC but increased NA in the PFC (Emax = 158 ± 26%). Local citalopram into the PFC enhanced NA (Emax = 376 ± 18%) in the area, which was prevented by MDL72222.

CONCLUSIONS

The SSRI citalopram modulates central noradrenergic neurotransmission by activation, through endogenous serotonin, of 5-HT3 receptors expressed in the somatodendritic (LC) and terminal (PFC) areas, which subsequently promote an enhancement of local NA. Therefore, 5-HT3 receptors and somatodendritic α2-adrenoceptors in the LC play an important role in the global effect of SSRIs.

Can low-dose propranolol induce a manic syndrome? Case report of an unexpected side effect

OBJECTIVES

Propranolol, the first discovered b-adrenergic receptor antagonist, has been prescribed by physicians in various fields for more than three decades. It has been applied for treating psychiatric disorders including schizophrenia, mania and anxiety disorders, as well as for controlling withdrawal symptoms or other side effects.

METHODS

We describe the case of an 11-year-old boy with bipolar-I disorder comorbid with panic disorder who developed manic symptoms with a single dose of 10 mg of propranolol. Results and Conclusion Although depression is a better-known side effect of b-adrenergic antagonists, clinicians should take mania as a rare side effect into consideration as well.

Rethinking 5-HT1A receptors: emerging modes of inhibitory feedback of relevance to emotion-related behavior

The complexities of the involvement of the serotonin transmitter system in numerous biological processes and psychiatric disorders is, to a substantial degree, attributable to the large number of serotonin receptor families and subtypes that have been identified and characterized for over four decades. Of these, the 5-HT(1A) receptor subtype, which was the first to be cloned and characterized, has received considerable attention based on its purported role in the etiology and treatment of mood and anxiety disorders. 5-HT(1A) receptors function both at presynaptic (autoreceptor) and postsynaptic (heteroreceptor) sites. Recent research has implicated distinct roles for these two populations of receptors in mediating emotion-related behavior. New concepts as to how 5-HT(1A) receptors function to control serotonergic tone throughout life were highlights of the proceedings of the 2012 Serotonin Club Meeting in Montpellier, France. Here, we review recent findings and current perspectives on functional aspects of 5-HT(1A) auto- and heteroreceptors with particular regard to their involvement in altered anxiety and mood states.

The dynamic interplay between negative and positive emotions in daily life predicts response to treatment in depression: a momentary assessment study

OBJECTIVES

Although the treatment of depressive illness aims to restore the imbalance between an excess of negative affect (NA) and a shortage of positive affect (PA), no study has examined how NA and PA may influence each other in depression. This study examines how NA and PA dynamically influence each other in depression and how this may impact on treatment response.

DESIGN

Depressed help-seeking individuals participated in the Experience Sampling Method (ESM), which enables visualization of subtle dynamic alterations of momentary affective states over time. Thereafter, participants received a combination of antidepressant treatment and psychotherapy, and were followed up each month.

METHODS

NA and PA were assessed during ESM at 10 random moments per day for 6 days. Depressive symptoms were assessed at baseline and at monthly intervals during treatment.

RESULTS

Future response to treatment was associated with altered baseline NA-PA dynamics in individuals with previous depressive episodes. Their daily life boosts of PA were followed by a stronger suppression of NA over subsequent hours than in other depressed groups or controls.

CONCLUSIONS

Subtle individual differences in daily life emotional dynamics predict future treatment outcome in depression.

Modifying 5-HT1A Receptor Gene Expression as a New Target for Antidepressant Therapy

Major depression is the most common form of mental illness, and is treated with antidepressant compounds that increase serotonin (5-HT) neurotransmission. Increased 5-HT1A autoreceptor levels in the raphe nuclei act as a “brake” to inhibit the 5-HT system, leading to depression and resistance to antidepressants. Several 5-HT1A receptor agonists (buspirone, flesinoxan, ipsapirone) that preferentially desensitize 5-HT1A autoreceptors have been tested for augmentation of antidepressant drugs with mixed results. One explanation could be the presence of the C(−1019)G 5-HT1A promoter polymorphism that prevents gene repression of the 5-HT1A autoreceptor. Furthermore, down-regulation of 5-HT1A autoreceptor expression, not simply desensitization of receptor signaling, appears to be required to enhance and accelerate antidepressant action. The current review focuses on the transcriptional regulators of 5-HT1A autoreceptor expression, their roles in permitting response to 5-HT1A-targeted treatments and their potential as targets for new antidepressant compounds for treatment-resistant depression.