Precision and comparability of adverse event rates of newer antidepressants

A novel concept of overcoming the skin barrier using augmented liquid nanocrystals: Box-Behnken optimization, ex vivo and in vivo evaluation

Agomelatine suffers from extensive inactivation through 1^st pass effect with a limited oral bioavailability (5%). The aim of this study was to formulate and optimize liquid nanocrystals (LNC) containing agomelatine to enhance the transdermal permeation of the drug. The independent factors of the employed Box-Behnken design were the Pluronic F127, deoxycholic acid sodium salt and propylene glycol percentages. On the other hand, particle size, polydispersity index, zeta potential, entrapment efficiency, cumulative amount permeated at certain time intervals and permeation enhancement ratio were considered as dependent responses. The optimized formulation was composed of 1.5% Pluronic F127 and 1.5% deoxycholic acid sodium salt and it was found to have significantly higher AUC_0-24h, AUC_0-∞ and elimination t_1/2 than that of the employed reference indicating the enhancement of the drug permeation. The obtained findings indicated the ability of the optimized LNC formulation to improve the drug bioavailability after its transdermal application.

Putative role of endocannabinoid signaling in the etiology of depression and actions of antidepressants

In the last few years, there have been several advances in the determination of the role of the endocannabinoid system in the etiology of depression and the functional actions of antidepressant drugs. Specifically, a deficiency in endocannabinoid signaling is sufficient to produce a "depressive-like" phenotype at the preclinical level (including changes in rewarding, emotional and cognitive behavior and biological changes such as increased HPA axis activity, impaired stress adaptation, reduced neurogenesis and altered serotonin negative feedback), and capable of inducing symptoms of depression in humans at a clinical level. In line with these findings, clinical populations diagnosed with depression are found to have reduced levels of circulating endocannabinoids and preclinical models of depression reveal a deficit in central endocannabinoid signaling. Moreover, facilitation of endocannabinoid signaling is sufficient to produce all of the behavioral and biochemical effects of conventional antidepressant treatments. Further, many forms of antidepressant treatments significantly alter endocannabinoid signaling, and in some of these cases this recruitment of endocannabinoid signaling is involved in the neuroadaptive effects of these treatments. Ultimately, these data present a compelling picture of the putative role of the endocannabinoid system in the processes subserving both the development and treatment of depression.

Better tolerability of St. John's wort extract WS 5570 compared to treatment with SSRIs: a reanalysis of data from controlled clinical trials in acute major depression

Selective serotonin reuptake inhibitors (SSRIs) like paroxetine have replaced older antidepressants mainly because of a more favorable safety profile, but they are still associated with burdensome side effects. We investigate the tolerability of St. John's wort extract WS 5570, a herbal antidepressant with proven efficacy, in comparison to paroxetine and other SSRIs and placebo. A reanalysis was performed based on the original data from four controlled clinical trials during which 1661 outpatients with major depression (Diagnostic and Statistical Manual of Mental Disorders, 4th Edition criteria) received between 600 and 1800 mg/day WS 5570 (n=1264), 20 or 40 mg/day paroxetine (n=126), or placebo (n=271) for 6 weeks. For single and grouped adverse events, the risk ratios for treatment group comparisons were determined along with their 95% confidence intervals, including comparisons with published data for SSRIs. Across the four trials, the percentage of patients with any adverse events under WS 5570 exposition was comparable with placebo [risk ratio (95% confidence interval): 1.1 (0.9-1.3) in favor of WS 5570] and significantly lower than for paroxetine [2.4 (2.1-2.8)]. Compared with the herbal extract adverse event rates under paroxetine were between 10 and 38-fold higher (point estimates) in five out of seven symptom clusters inspected. WS 5570 was devoid of effects of sedation, anticholinergic reactions, gastrointestinal disturbances, and sexual dysfunction often found during treatment with SSRIs and other synthetic antidepressants. In conclusion, WS 5570 exhibits substantially lower incidence rates of adverse events than paroxetine and other SSRIs.

Beyond the monoaminergic hypothesis: agomelatine, a new antidepressant with an innovative mechanism of action

There are many potentials for the development of more effective, better tolerated, and more rapidly acting antidepressants. As there is large prevalence of circadian dysfunction in various affective disorders, including depression, one of the approaches is the development of antidepressant drugs with melatonergic agonist properties. Agomelatine, with its melatonergic agonistic (at both MT(1) an MT(2) receptors) and 5-HT(2C) antagonistic properties, represents a new concept for the treatment of depression. The antidepressant action of agomelatine has been initially demonstrated in animal models of depression, such as the forced swim - the learned helplessness - and the chronic mild stress paradigms. Subsequent studies demonstrated that the antidepressant activity of agomelatine does not solely depend on its agonistic action at melatonergic receptors, but also on its antagonistic activity at 5-HT(2C) receptors. Agomelatine also exhibits anxiolytic properties that bear a striking resemblance to those of selective 5-HT(2C) receptor antagonists. In patients with major depressive disorder, agomelatine had efficacy at least comparable to that seen with available antidepressants. Interestingly, agomelatine demonstrated antidepressant efficacy not only in patients with a moderate depressive episode but also in a more severe depressed subpopulation of patients. The treatment effect increased with the severity of the disease. Agomelatine also rapidly regulates the sleep-wake cycle without causing sedation and improves daytime condition. Agomelatine has an excellent safety profile, is weight neutral, does not affect sexual functioning and does not cause discontinuation syndrome. Collectively, its efficacy, together with its excellent tolerability, makes agomelatine an especially promising antidepressant for the near future.

D-161, a novel pyran-based triple monoamine transporter blocker: behavioral pharmacological evidence for antidepressant-like action

Deficiency in dopaminergic activity has been linked to a depressed state in pharmacological and clinical studies. Current pharmacological treatment for depression primarily involves modulation of serotonergic and noradrenergic systems but not dopaminergic neurotransmission. Available pharmacotherapy for depression has a number of drawbacks as a significant number of people are either refractory or develop tolerance to the antidepressant agents resulting in relapse. Furthermore, the slow onset of action of current therapies often poses a challenge for effective treatment. In our effort to develop novel molecules impacting all three above mentioned monoamine systems, we discovered structurally unique pyran derivatives with various profiles in inhibiting monoamine transporters. One of our lead molecules, D-161 exhibited triple monoamine transporter inhibitory activity with the highest affinity for norepinephrine transporter (NET) followed by its affinity for serotonin transporter (SERT) and dopamine transporter (DAT). D-161 exhibited potent activity in reducing immobility significantly in the rat forced swim test as well as in the mouse tail suspension test. Moreover, results from locomotor activity tests indicated that the reduction of immobility by D-161 was not due to motor activation as no significant motor activation was observed when the rats were subjected to the same doses of drug under the same conditions as in the forced swim test. These results suggest that the novel asymmetric pyran derivative D-161 with unique molecular structure exhibiting triple monoamine transporter inhibitory activity could possess potent antidepressant activity.

Adverse cardiovascular events in antidepressant trials involving high-risk patients: a systematic review of randomized trials

OBJECTIVE

To examine whether selective serotonin reuptake inhibitor (SSRI) antidepressants were associated with an increased or decreased risk of cardiovascular adverse events (AEs).

METHODS

We conducted a systematic review of randomized controlled trials published between 1967 and May 2005 that treated patients with cardiac disease, diabetes mellitus, stroke, geriatric age, nicotine dependence, alcoholism, HIV infection, and obesity. We defined serious AEs as death due to a cardiovascular cause, heart failure, stroke, transient ischemic attack, and myocardial infarction. Nonserious AEs were defined as palpitations, chest pain, angina, arrhythmia, hypertension, hypotension-syncope, and unspecified cardiovascular or neurologic events. Adverse event rates were calculated in 4 groups: SSRIs, tricyclic antidepressants (TCAs), other active therapies, and placebo.

RESULTS

Stroke and cardiac patients were the highest-risk groups for cardiovascular AEs. We were unable to detect differences in odds between SSRI and placebo for both serious (odds ratio [OR] 0.69; 95% confidence interval [CI], 0.39 to 1.21) and nonserious (OR 1.18; 95% CI, 0.90 to 1.57) cardiovascular AEs. There was a significant decrease in the odds of nonserious cardiovascular AEs (OR 0.46; 95% CI, 0.24 to 0.86, P = 0.02) for patients receiving SSRIs, compared with TCAs. Over one-half of the selected trials did not report the presence or absence of cardiovascular events.

CONCLUSIONS

This systematic review of antidepressant trials in high-risk patients did not determine whether SSRIs are associated with a greater or lesser risk of cardiovascular AEs. Reasons for this conclusion include the rarity of serious AEs, the lack of large trials in these patients, and a lack of adequate reporting of AEs in published trials. Further trials assessing the risk of cardiovascular AEs and better trial reporting are needed.

Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application

Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.

Serotonin 5-HT2C receptors as a target for the treatment of depressive and anxious states: focus on novel therapeutic strategies

Serotonin (5-HT)2C receptors play an important role in the modulation of monoaminergic transmission, mood, motor behaviour, appetite and endocrine secretion, and alterations in their functional status have been detected in anxiodepressive states. Further, 5-HT2C sites are involved in the actions of several classes of antidepressant. At the onset of treatment, indirect activation of 5-HT2C receptors participates in the anxiogenic effects of selective 5-HT reuptake inhibitors (SSRIs) as well as their inhibition of sleep, sexual behaviour and appetite. Conversely, progressive down-regulation of 5-HT2C receptors parallels the gradual onset of clinical efficacy of SSRIs. Other antidepressants, such as nefazodone or mirtazapine, act as direct antagonists of 5-HT2C receptors. These observations underpin interest in 5-HT2C receptor blockade as a strategy for treating depressive and anxious states. This notion is supported by findings that 5-HT2C receptor antagonists stimulate dopaminergic and adrenergic pathways, exert antidepressant and anxiolytic actions in behavioural paradigms, and favour sleep and sexual function. In addition to selective antagonists, novel strategies for exploitation of 5-HT2C receptors embrace inverse agonists, allosteric modulators, ligands of homo/heterodimers, modulators of interactions with 'postsynaptic proteins', dual melatonin agonists/5-HT2C receptor antagonists and mixed 5-HT2C/alpha2-adrenergic antagonists. Intriguingly, there is evidence that stimulation of regionally discrete populations of 5-HT2C receptors is effective in certain behavioural models of antidepressant activity, and promotes neurogenesis in the hippocampus. This article explains how these ostensibly paradoxical actions of 5-HT2C antagonists and agonists can be reconciled and discusses both established and innovative strategies for the exploitation of 5-HT2C receptors in the improved management of depressed and anxious states.

Is there a role for the endocannabinoid system in the etiology and treatment of melancholic depression?

With advances in basic and clinical neuroscience, many gaps have appeared in the traditional monoamine theory of depression that have led to reformulation of the hypotheses concerning the neurobiology of depression. The more recent hypotheses suggest that melancholic depression is characterized by central glucocorticoid resistance that results in hypercortisolemia, which in turn leads to down-regulation of neurotrophins and subsequent neurodegeneration. Examining the neurobiology of depression from this perspective suggests that the endocannabinoid system may play a role in the etiology of melancholic depression. Specifically, pharmacological and genetic blockade of the cannabinoid CB1 receptor induces a phenotypic state that is analogous to melancholic depression, including symptoms such as reduced food intake, heightened anxiety, increased arousal and wakefulness, deficits in extinction of aversive memories and supersensitivity to stress. These similarities between melancholic depression and an endocannabinoid deficiency become more interesting in light of recent findings that endocannabinoid activity is down-regulated by chronic stress and possibly increased by some antidepressant regimens. We propose that an endocannabinoid deficiency may underlie some of the symptoms of melancholic depression, and that enhancement of this system may ultimately be a novel form of pharmacotherapy for treatment-resistant depression.

Comment déveloper un antidépresseur au mécanisme d’action innovant : l’exemple de l’agomélatine

There are now many potentials for the development of more effective, better tolerated, and more rapidly acting antidepressants acting in association and/or beyond the monoamine hypothesis. One of these possibilities is the development of antidepressant drugs with melatonin agonist property. This holds much promise since various affective disorders, including depression, are characterized by abnormal patterns of circadian rhythms. In line with this, the melatoninergic agonist properties of agomelatine, an antidepressant with proven clinical efficacy, may represent a new concept for the treatment of depression. By way of behavioral studies in rodents, it has been shown that administration of agomelatine can mimic the action of melatonin in the synchronization of circadian rhythm patterns. Interest in agomelatine has increased in recent times due to its prospective use as a novel antidepressant agent, as demonstrated in a number of animal studies using well-validated animal models of depression (including the forced swimming test, the learned helplessness, the chronic mild stress). Interestingly, the melatoninergic agonist property of agomelatine may not, alone, be sufficient to sustain its clear antidepressant-like activity. Recent results from receptor binding and in vivo studies gave support to the notion that agomelatine's effects are also mediated via its function as a competitive antagonist at the 5-HT2C receptor. Finally, thanks to its absence of binding with a broad range of receptors and enzymes, agomelatine is particularly safe and devoid of all the deleterious effects reported with tricyclics and SSRIs.

The role of monoamines in the actions of established and "novel" antidepressant agents: a critical review

Monoaminergic pathways are highly responsive to aversive stimuli and play a crucial role in the control of affect, cognition, endocrine secretion, chronobiotic rhythms, appetite, and motor function, all of which are profoundly disrupted in depressive states. Accordingly, a perturbation of monoaminergic transmission is implicated in the aetiology of depressive disorders, and all clinically available antidepressants increase corticolimbic availability of monoamines. However, their limited efficacy, delayed onset of action, and undesirable side effects underlie ongoing efforts to identify improved therapeutic agents. Sequencing the human genome has raised the hope not only of better symptomatic control of depression, but even of the prevention or cure of depressive states. In the pursuit of these goals, there is currently a tendency to focus on selective ligands of "novel" nonmonoaminergic targets. However, certain classes of novel agent (such as neurokinin(1) receptor antagonists) indirectly modulate the activity of monoaminergic networks. Others may act "downstream" of them, converging onto common cellular substrates controlling gene expression, synaptic plasticity, and neurogenesis. Further, by analogy to the broad-based actions of currently employed drugs, multitarget agents may be better adapted than selective agents to the management of depression-a complex disorder with hereditary, developmental, and environmental origins. It is, thus, important to continue the creative exploration of clinically validated and innovative monoaminergic strategies within a multitarget framework. In this light, drugs combining monoaminergic and nonmonoaminergic mechanisms of action may be of particular interest. The present article provides a critical overview of monoaminergic strategies for the treatment of depressive states, both established and under development, and discusses interactions of novel "nonmonoaminergic" antidepressants with monoaminergic mechanisms.

The pharmacovigilance of psychoactive medications in Brazil

OBJETIVE: The present study aimed to analyze 219 notifications of suspected adverse reactions (AR) produced by psychoactive medicaments (ARPM), notified by Brazilian psychiatrists, during a 3-month period (April 1999 up to September 2001). METHOD: A notifying card for adverse reactions possibly produced by psychoactive medications was quarterly sent to all psychiatrists affiliated to the Brazilian Association of Psychiatry. Once each notification, dully filled in, was received, the possible adverse reaction was analyzed in order to verify the causality RESULTS: The psychiatrists classified as severe 50 of the ARPMs; 150 others were not considered as severe. Among the severe ones there were 3 deaths, 12 life-threatening reactions, 26 ARPMs required or prolonged hospitalization and 9 notifications described temporary disability of the patients. Among the medications, antidepressants ranked first with 122 ARPMs being notified, followed by neuroleptics (46 ARPMs) and antiepiletic medicaments (25 ARPMs). The three main organs and systems affected by the ARs were the Central Nervous System with 102 ARs, skin and mucosa with 44 and gastrointestinal with 21 ARPMs. CONCLUSION: Considering causality, i.e., the association between the medication and the described AR, 24 cases were considered as Definite (with positive dechallenge and rechallenge, i.e., withdrawal and reintroduction of the medication) and 134 other ARPMs were classified as Probable (only dechallenge positive; only with medication withdrawal; rechallenge was not performed).

Moclobemide: therapeutic use and clinical studies

Moclobemide is a reversible inhibitor of monoamine-oxidase-A (RIMA) and has been extensively evaluated in the treatment of a wide spectrum of depressive disorders and less extensively studied in anxiety disorders. Nearly all meta-analyses and most comparative studies indicated that in the acute management of depression this drug is more efficacious than placebo and as efficacious as tricyclic (or some heterocyclic) antidepressants or selective serotonin reuptake inhibitors (SSRIs). There is a growing evidence that moclobemide is not inferior to other antidepressants in the treatment of subtypes of depression, such as dysthymia, endogenous (unipolar and bipolar), reactive, atypical, agitated, and retarded depression as with other antidepressants limited evidence suggests that moclobemide has consistent long-term efficacy. However, more controlled studies addressing this issue are needed. For patients with bipolar depression the risk of developing mania seems to be not higher with moclobemide than with other antidepressants. The effective therapeutic dose range for moclobemide in most acute phase trials was 300 to 600 mg, divided in 2 to 3 doses. While one controlled trial and one long-term open-label study found moclobemide to be efficacious in social phobia, three controlled trials subsequently revealed either no effect or less robust effects with the tendency of higher doses (600 - 900 mg/d) to be more efficacious. Two comparative trials demonstrated moclobemide to be as efficacious as fluoxetine or clomipramine in patients suffering from panic disorder. Placebo-controlled trials in this indication are, however, still lacking. A relationship between the plasma concentration of moclobemide and its therapeutic efficacy is not apparent but a positive correlation with adverse events has been found. Dizziness, nausea and insomnia occurred more frequently on moclobemide than on placebo. Due to negligible anticholinergic and antihistaminic actions, moclobemide has been better tolerated than tri- or heterocyclic antidepressants. Gastrointestinal side effects and, especially, sexual dysfunction were much less frequent with moclobemide than with SSRIs. Unlike irreversible MAO-inhibitors, moclobemide has a negligible propensity to induce hypertensive crisis after ingestion of tyramine-rich food ("cheese-reaction"). Therefore, dietary restrictions are not as strict. However, with moclobemide doses above 900 mg/d the risk of interaction with ingested tyramine might become clinically relevant. After multiple dosing the oral bioavailability of moclobemide reaches almost 100%. At therapeutic doses, moclobemide lacks significant negative effects on psychomotor performance, cognitive function or cardiovascular system. Due to the relative freedom from these side effects, moclobemide is particularly attractive in the treatment of elderly patients. Moclobemide is a substrate of CYP2C19. Although it acts as an inhibitor of CYP1A2, CYP2C19, and CYP2D6, relatively few clinically important drug interactions involving moclobemide have been reported. It is relatively safe even in overdose. The drug has a short plasma elimination half-life that allows switching to an alternative agent within 24 h. Since it is well tolerated, therapeutic doses can often be reached rapidly upon onset of treatment. Steady-state plasma levels are reached approximately at one week following dose adjustment. Patients with renal dysfunction require no dose reduction in contrast to patients with severe hepatic impairment. Cases of refractory depression might improve with a combination of moclobemide with other antidepressants, such as clomipramine or a SSRI. Since this combination has rarely been associated with a potentially lethal serotonin syndrome, it requires lower entry doses, a slower dose titration and a more careful monitoring of patients. Combination therapy with moclobemide and other serotonergic agents, or opioids, should be undertaken with caution, although no serious adverse events have been published with therapeutic doses of moclobemide to date. On the basis of animal data the combined use of moclobemide with pethidine or dextropropoxyphene should be avoided. There is no evidence that moclobemide would increase body weight or produce seizures. Some preclinical data suggest that moclobemide may have anticonvulsant property.

Antidepressant side effects in depression patients treated in a naturalistic setting: a study of bupropion, moclobemide, paroxetine, sertraline, and venlafaxine

OBJECTIVE

There is no commonly accepted standard for comparing antidepressant-induced side effects. This study evaluates a clinician-administered scale, the Toronto Side Effect Scale (TSES), in a natural practice clinic.

METHOD

We used the TSES to assess side effects in 193 depression patients who completed 8 weeks of treatment with either bupropion, moclobemide, paroxetine, sertraline, or venlafaxine.

RESULTS

Rates of remission (Hamilton Rating Scale for Depression [HRSD] < 7) did not differ across drugs after 8 weeks of treatment. Paired drug comparisons yielded significant differences in 16 of the 32 side effects. We present differences between pairs of the 5 antidepressants in Central Nervous System (CNS), gastrointestinal (GI), and sexual side effects. A measure of side-effect intensity distinguished paroxetine from the other antidepressants on a measure of sexual dysfunction.

CONCLUSIONS

These results confirm the clinical utility of the TSES as a simple, clinician-administered antidepressant side-effect scale.