Mirtazapine, a Novel Antidepressant, in the Treatment of Anxiety Symptoms: Results from a Placebo-Controlled Trial

Real-world, open-label study to evaluate the effectiveness of mirtazapine on sleep quality in outpatients with major depressive disorder

INTRODUCTION

The objective of this study was to evaluate the effect of mirtazapine on sleep quality in real-world outpatients with major depressive disorder (MDD).

METHODS

Demographic characteristics of MDD outpatients were collected and the Pittsburgh Sleep Quality Index (PSQI) was assessed before and after treatment.

RESULTS

In 3,924 MDD outpatients after treatment, sleep efficiency was significantly higher (P < 0.001), global PSQI score was significantly lower (P < 0.01), the reduction rates of sleep latency (P < 0.01) and global PSQI score (P < 0.001) were notably higher, and the proportion of using sleep medications (P < 0.05) was significantly lower in the mirtazapine group. In 3,455 MDD outpatients with insomnia after treatment, the reduction of sleep latency (P < 0.001), the prolongation of sleep duration (P < 0.001), and the increase in habitual sleep efficiency (P < 0.001) were more obvious, the reduction rates of sleep latency (P < 0.05) and global PSQI score (P < 0.001) were significantly higher, and the proportion of using sleep medications (P < 0.001) was significantly lower in the mirtazapine group. In 469 MDD outpatients without insomnia after treatment, the reduction of sleep latency (P < 0.05), the increase in sleep duration (P < 0.001) and habitual sleep efficiency (P < 0.001), and the reduction rate of global PSQI score (P < 0.05) were significantly greater in the mirtazapine group.

DISCUSSION

This real-world study suggests that mirtazapine improves sleep quality of MDD outpatients, and decreases the concomitant use of sleep medications.

Mirtazapine treatment of generalized anxiety disorder: a fixed dose, open label study

We investigated the efficacy of mirtazapine in the treatment of generalized anxiety disorder (GAD). Forty-four adult outpatients with GAD were treated openly with a fixed dose of mirtazapine (30 mg) for 12 weeks. The primary outcome measure was the change from baseline in total score on the Hamilton Rating Scale for Anxiety (HAM-A). The Clinical Global Impression of Improvement (CGI-I) was rated at the endpoint. Patients with a reduction of 50% or more on the HAM-A total score and a CGI-I score of 1 or 2 at endpoint were considered responders to treatment; remission was defined as a HAM-A score <or=7. At 12 weeks, response was achieved by 79.5% of the patients (n=35) and remission by 36.4% of patients (n=16). This study supports the notion that mirtazapine is an efficacious and well tolerated treatment for GAD. Limitations of the present study must be considered and further placebo-controlled trials are needed.

Mirtazapine in social anxiety disorder: a pilot study

Fourteen patients with social anxiety disorder (generalized type), according to DSM-IV criteria, were treated with mirtazapine 30 mg for 12 weeks. Twelve patients completed the study. Two patients (14.3%) dropped out due to side-effects. Generally, mirtazapine was well tolerated. Five out of 12 patients (41.7%) were classified as responders, based on a Clinical Global Improvement score of 1 or 2 and a reduction of the Liebowitz Social Anxiety Scale (LSAS) of 40%. The mean total score on the LSAS, as well as the anxiety and avoidance subscores, decreased significantly. This open pilot study suggests that further investigations are warranted to prove the efficacy of mirtazapine in generalized social anxiety disorder.

Review of the results from clinical studies on the efficacy, safety and tolerability of mirtazapine for the treatment of patients with major depression

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.

Depression in community-dwelling elders. Overcoming treatment obstacles with new antidepressants

Although depression is the most common psychiatric disorder among older adults, it continues to be misdiagnosed and undertreated in this population for a variety of reasons. The authors present an overview of the efficacy and side effects of antidepressant medications, pointing out advantages of new drugs that are especially important in older patients.

Advantages and limitations of the concept of antidepressant therapy

The current availability of a range of effective treatments make it more than ever necessary for depression to be recognised. The emphasis of treatment has moved from acute episodes to the longitudinal course of affective disorders. In addition to Major Depressive Disorder, the need for treatment is now established in less severe variants, particularly Dysthymia; the same drugs are applicable, but should be part of a global strategy. In general, antidepressants have to be considered in relation to non-pharmacological treatment methods, of which the most important is ECT. A great variety of new drugs have been found to have antidepressant efficacy, but pharmacologically this action is not a specific or exclusive one. Side-effects have on the whole not been studied for long enough, or in depressed patients rather than healthy volunteers; there are marked variations between individuals in their reactions to different drugs. Co-morbidity is a frequent issue in the treatment of depression, particularly for the elderly. Since overall suicide rates have not fallen in many countries, the treatment particularly of Major Depressive Disorder and Bipolar Disorder needs to be strengthened.