Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P46098 (5-HT3 receptor)
 2,290 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mirtazapine is a presynaptic alpha-2 antagonist that has dual action by increasing noradrenergic and serotonergic neurotransmission. The enhancement of serotonergic neurotransmission is specifically mediated via 5-HT1 receptors because mirtazapine is a postsynaptic serotonergic 5-HT2 and 5-HT3 antagonist. In addition, mirtazapine has only a weak affinity for 5-HT1 receptors and has very weak muscarinic anticholinergic and histamine (H1) antagonist properties. As a consequence of its unique pharmacodynamic properties, mirtazapine is an effective, safe and well-tolerated addition to the antidepressant armamentarium. Mirtazapine is well absorbed from the gastrointestinal tract following oral administration, and it is extensively metabolized in the liver to four metabolites via demethylation and hydroxylation, followed by glucuronide conjugation. The unconjugated desmethyl metabolite is pharmacologically less active than the parent compound. Mirtazapine lacks auto-induction of hepatic isoenzymes. Although mirtazapine is a substrate of P450 isoenzymes 1A2, 2D6 and 3A4, in vitro studies show that it is not a potent inhibitor or inducer of any of these enzymes. Mirtazapine has been evaluated in a worldwide clinical development program involving approximately 4500 patients. Controlled clinical trials involving almost 2800 mirtazapine-treated patients have demonstrated the compound to be effective for the treatment of moderate-to-serve major depression. Mirtazapine was consistently superior to placebo, and equivalent in efficacy to the tricyclic antidepressants amitriptyline, doxepin and clomipramine, but with an improved tolerability profile. Mirtazapine has shown a rapid onset of action in patients with predominantly severe depressive illness in a comparative study against fluoxetine. Mirtazapine has a unique tolerability profile, since the specific postsynaptic 5-HT2 and 5-HT3 receptor blockade of mirtazapine provides early antidepressant effects without causing unwanted serotonin-related side-effects. Transient somnolence, hyperphagia and weight gain are the most commonly reported adverse events, which may be attributed to the antihistaminic (H1) activity of mirtazapine at low doses. Somnolence, the most commonly reported side-effect, appears to be less frequent at higher dosages. Mirtazapine also demonstrates important anxiolytic and sleep-improving effects, which may be related to its pharmacodynamic properties. In addition, mirtazapine does not appear to be associated with sexual dysfunction. Mirtazapine has shown no significant cardiovascular adverse effects at multiples of 7 to 22 times the maximum recommended dose. Mirtazapine is a unique addition to the antidepressant armamentarium as first-line therapy in patients with major depression and symptoms of anxiety/agitation or anxiety/somatization or complaints of insomnia and as a useful alternative in depressed patients who do not adequately respond to or are intolerant of tricyclic antidepressants or serotonin-specific reuptake inhibitors.
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PMID:Review of the results from clinical studies on the efficacy, safety and tolerability of mirtazapine for the treatment of patients with major depression. 1033 82

Antidepressant induced sexual dysfunction is a common adverse event that is particularly evident with serotonergic antidepressants. There is a paucity of clinical trial evidence on the treatment of this problem. While there is some evidence of involvement of the serotonin (5-HT2) receptor subtype in this phenomenon, other serotonergic receptor systems are not well studied. In this trial, 35 patients on maintenance therapy with a variety of serotonergic antidepressants, who reported antidepressant induced sexual dysfunction, were enrolled. Patients were given both granisetron 1 mg, and sumatriptan 100 mg, in a crossover design, to be used 1 h before intercourse. Sexual dysfunction was measured using the Feiger scale. There was a high dropout rate in the trial, reflecting both embarrassment with the pharmacological treatment of sexual dysfunction and difficulties with planning and timing the medication. Nevertheless, there was a significant effect of granisetron in this study, with scores decreasing from 23.7 (SD 2.52) to 16.0 (SD 6.42) on the Feiger scale (n = 14, P = 0.001, Wilcoxon sign rank test). Sumatriptan failed to show a significant change from baseline at the 0.01 level of significance. While the small sample size, high dropout rates and open label design are limitations to this study, it suggests efficacy of the granisetron in antidepressant induced sexual dysfunction and the role of the 5-HT3 receptor in this phenomenon.
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PMID:Serotonergic targets in the treatment of antidepressant induced sexual dysfunction: a pilot study of granisetron and sumatriptan. 1099 31

SSRI-induced sexual dysfunction affects 30% to 50% or more of individuals who take these drugs for depression. Biochemical mechanisms suggested as causative include increased serotonin, particularly affecting 5HT2 and 5HT3 receptors; decreased dopamine; blockade of cholinergic and alpha-1 adrenergic receptors; inhibition of nitric oxide synthetase; and elevation of prolactin levels. Five approaches to treatment include conservative approaches such as wait and see, decrease dosage, and drug holidays. More aggressive strategy for treating SSRI-induced sexual dysfunction are changing antidepressants and augmentation.
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PMID:Mechanisms and treatments of SSRI-induced sexual dysfunction. 1238 82

Lu-AA21004, an oral, multimodal serotonergic agent, is currently under development by H Lundbeck and Takeda Pharmaceutical, for the potential treatment of depression and anxiety. Lu-AA21004 belongs to a novel chemical class of antidepressant agents, the bisarylsulfanyl amines, and possesses a novel pharmacological profile, with activity at serotonergic receptors 5-HT3, 5-HT7 and 5-HT1A, and also at the 5-HT transporter. Acute administration of Lu-AA21004 in rats inhibited the firing activity of serotonergic neurons of the dorsal raphe nucleus through 5-HT3 receptor blockade, with rapid recovery of firing activity upon cessation of treatment compared with an antidepressant of the SSRI class. Results from phase II clinical trials have reported improvement in depression and anxiety symptoms after 6 weeks of treatment. Lu-AA21004 was generally well tolerated, with adverse events related to sexual dysfunction occurring in a lower number of patients receiving Lu-AA21004 compared with venlafaxine. Phase III clinical trials with Lu-AA21004 in patients with major depressive disorder are underway and phase III trials in patients with generalized anxiety disorder have been completed. If initial outcomes from these clinical trials prove positive, Lu-AA21004 may pave the way for new multimodal therapies for the treatment of depression and anxiety.
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PMID:Lu-AA21004, a multimodal serotonergic agent, for the potential treatment of depression and anxiety. 2115 50

The current generation of antidepressant drugs acts predominantly by targeting the serotonin transporter (SERT). The original trend to do this selectively (e.g., with SSRIs or selective serotonin reuptake inhibitors) has given way to combining various additional pharmacologic mechanisms with SERT inhibition, including dual actions by single drugs (e.g., SNRIs or serotonin norepinephrine reuptake inhibitors), or by augmenting SSRIs with a second drug of a different mechanism (e.g., bupropion with dopamine and norepinephrine reuptake inhibition; trazodone with 5HT2A antagonism; mirtazapine with 5HT2A/5HT2C/5HT3/alpha2 antagonism; buspirone or some atypical antipsychotics with 5HT1A partial agonism; other atypical antipsychotics with 5HT2C/5HT7 antagonism and other mechanisms). Novel drugs in development include those that combine multiple simultaneous pharmacologic mechanisms in addition to SERT inhibition within the same molecule, such as vilazodone (combining 5HT1A partial agonism with SERT inhibition), triple reuptake inhibitors (combining norepinephrine and dopamine reuptake inhibition with SERT inhibition), and vortioxetine, a multimodal antidepressant combining actions at the G protein receptor mode (5HT1A and 5HT1B partial agonism and 5HT7 antagonism), at the ion channel mode (5HT3 antagonism) as well as the neurotransmitter transporter mode (SERT inhibition). These various strategies that build upon SERT inhibition provide promise for novel therapeutic approaches to depression, including the possibility of targeting residual symptoms not well treated by SERT inhibition alone, and reducing side effects, such as sexual dysfunction.
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PMID:Serotonergic drugs for depression and beyond. 2353 Nov 15

Vortioxetine, a novel antidepressant for the treatment of major depressive disorder (MDD), is a 5-HT3, 5-HT7 and 5-HT1D receptor antagonist, 5-HT1B receptor partial agonist, 5-HT1A receptor agonist and serotonin (5-HT) transporter (SERT) inhibitor. Here we review its preclinical and clinical properties and discuss translational aspects. Vortioxetine increases serotonergic, noradrenergic, dopaminergic, cholinergic, histaminergic and glutamatergic neurotransmission in brain structures associated with MDD. These multiple effects likely derive from its interaction with 5-HT-receptor-mediated negative feedback mechanisms controlling neuronal activity. In particular, 5-HT3 receptors may play a prominent role, since their blockade i) increases pyramidal neuron activity by removing 5-HT3 receptor-mediated excitation of GABA interneurons, and ii) augments SSRI effects on extracellular 5-HT. However, modulation of the other 5-HT receptor subtypes also likely contributes to vortioxetine's pharmacological effects. Preclinical animal models reveal differences from SSRIs and SNRIs, including antidepressant-like activity, increased synaptic plasticity and improved cognitive function. Vortioxetine had clinical efficacy in patients with MDD: 11 placebo-controlled studies (including one in elderly) with efficacy in 8 (7 positive, 1 supportive), 1 positive active comparator study plus a positive relapse prevention study. In two positive studies, vortioxetine was superior to placebo in pre-defined cognitive outcome measures. The clinically effective dose range (5-20mg/day) spans ~50 to >80% SERT occupancy. SERT and 5-HT3 receptors are primarily occupied at 5mg, while at 20mg, all targets are likely occupied at functionally relevant levels. The side-effect profile is similar to that of SSRIs, with gastrointestinal symptoms being most common, and a low incidence of sexual dysfunction and sleep disruption possibly ascribed to vortioxetine's receptor modulation.
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PMID:Vortioxetine, a novel antidepressant with multimodal activity: review of preclinical and clinical data. 2501 86