A multicentre, double-blind, amitriptyline-controlled study of mirtazapine in patients with major depression

A review of therapeutic uses of mirtazapine in psychiatric and medical conditions

OBJECTIVE

To review the literature examining the use of mirtazapine with an emphasis on its therapeutic benefits for psychiatric patients with comorbid medical conditions.

DATA SOURCES

MEDLINE, PsycINFO, Global Health, and AGRICOLA were searched using the terms mirtazapine OR Remeron. Limits were English language, human, year 1980-2012, treatment and prevention, and therapy.

STUDY SELECTION

Two hundred ninety-three articles were identified.

DATA EXTRACTION

Identified articles were reviewed with a focus on indications and therapeutic benefits in patients with medical comorbidities.

RESULTS

Mirtazapine is an effective antidepressant with unique mechanisms of action. It is characterized by a relatively rapid onset of action, high response and remission rates, a favorable side-effect profile, and several unique therapeutic benefits over other antidepressants. Mirtazapine has also shown promise in treating some medical disorders, including neurologic conditions, and ameliorating some of the associated debilitating symptoms of weight loss, insomnia, and postoperative nausea and vomiting.

CONCLUSIONS

Mirtazapine offers clinicians multiple therapeutic advantages especially when treating patients with comorbid medical illness.

Mirtazapine versus other antidepressive agents for depression

BACKGROUND

Mirtazapine has a unique mechanism of antidepressive action and is one of the commonly used antidepressants in clinical practice.

OBJECTIVES

The aim of the present review was to assess the evidence on the efficacy and acceptability of mirtazapine compared with other antidepressive agents in the acute-phase treatment of major depression in adults.

SEARCH METHODS

We searched the Cochrane Collaboration Depression, Anxiety and Neurosis review group's specialised register (CCDANCTR), which includes relevant randomised controlled trials from the following bibliographic databases: The Cochrane Library (all years to April 2011), EMBASE, (1980 to July 2011) MEDLINE (1950 to July 2011) and PsycINFO (1974 to July 2011). Reference lists of the reports of relevant studies were checked and experts in the field contacted. The review was not limited to English-language articles.

SELECTION CRITERIA

Randomised controlled trials (RCTs) allocating participants with major depression to mirtazapine versus any other antidepressive agent.

DATA COLLECTION AND ANALYSIS

Two authors independently checked eligibility and extracted data on an intention-to-treat basis. The primary outcome was response to treatment. The secondary outcomes included dropouts and individual adverse events.Meta-analyses were conducted using the random-effects model.

MAIN RESULTS

A total of 29 RCTs (n = 4974), mostly following up the participants for six weeks in outpatient clinics and inadequately reporting the risk of bias, were included. In comparison with tricyclic antidepressants (10 trials, n = 1553) there was no robust evidence to detect a difference between mirtazapine and tricyclics in terms of response at two weeks (odds ratio (OR) 0.85, 95% confidence interval (CI) 0.64 to 1.13) or at the end of acute-phase treatment (at 6 to 12 weeks) (OR 0.89, 95% CI 0.72 to 1.10). In comparison with selective serotonin reuptake inhibitors (SSRIs) (12 trials, n = 2626) mirtazapine was significantly more effective at two weeks (OR 1.57, 95% CI 1.30 to 1.88) and at the end of acute-phase treatment (OR 1.19, 95% CI 1.01 to 1.39). Mirtazapine was significantly more effective than a serotonin-noradrenaline reuptake inhibitor (venlafaxine only, two trials, n = 415) at two weeks (OR 2.29, 95% CI 1.45 to 3.59) and at the end of acute-phase treatment (OR 1.53, 95% CI 1.03 to 2.25).In terms of dropouts, there was no robust evidence to detect a difference between mirtazapine and other antidepressants. Mirtazapine was more likely to cause weight gain or increased appetite and somnolence than SSRIs but less likely to cause nausea or vomiting and sexual dysfunction.

AUTHORS' CONCLUSIONS

Some statistically significant and possibly clinically meaningful differences between mirtazapine and other antidepressive agents were found for the acute-phase treatment of major depression. Mirtazapine is likely to have a faster onset of action than SSRIs during the acute-phase treatment. Dropouts occur similarly in participants treated with mirtazapine and those treated with other antidepressants, although the adverse event profile of mirtazapine is unique.

Mirtazapine: a review of its use in major depression and other psychiatric disorders

Mirtazapine (Remeron, Zispin) is a noradrenergic and specific serotonergic antidepressant (NaSSA) that is approved in many counties for use in the treatment of major depression. Monotherapy with mirtazapine 15-45 mg/day leads to rapid and sustained improvements in depressive symptoms in patients with major depression, including the elderly. It is as effective as other antidepressants and may have a more rapid onset of action than selective serotonin reuptake inhibitors (SSRIs). Furthermore, it may also have a higher sustained remission rate than amitriptyline. Preliminary data suggest that mirtazapine may also be effective in the treatment of anxiety disorders (including post-traumatic stress disorder, panic disorder and social anxiety disorder), obsessive-compulsive disorder, undifferentiated somatoform disorder and, as add-on therapy, in schizophrenia, although large, well designed trials are needed to confirm these findings. Mirtazapine is generally well tolerated in patients with depression. In conclusion, mirtazapine is an effective antidepressant for the treatment of major depression and also has the potential to be of use in other psychiatric indications.

The results of the Swiss observational study of the new, fast-dissolving mirtazapine formulation in depressed patients

Objective. The purpose of the present study was to document the experience with the use of a new, fast-dissolving oral tablet (FDT, RemeronSolTab®) of mirtazapine, a NaSSA antidepressant, in the treatment of depressed patients in daily practice in Switzerland. Methods. It was an open, prospective collection of observations in a total of 1121 depressive patients (>18 years old, both sexes). The treatment duration was 8 weeks with assessments after the second and eighth week. Efficacy measures were CGI (seven points) and specific check-lists for the ratings of severity of anxiety and sleep disturbances. At the end of the trial the acceptance (eight-item questionnaire) of the new formulation was recorded too. Results. The results showed that there was highly significant (P<0.001) and rapid improvement of severity of depression, anxiety and sleep disturbances in the whole population. Subgroup analyses showed that the antidepressant efficacy was independent of gender, initial severity of depression or of the type of depression (first episode, recurrent, chronic depression). The majority of patients (80%) liked at least one of the properties of FDT and, out of 75% of patients having experience with conventional tablet, 50% stated to be better compliant with this new formulation. Conclusion. This report documents the antidepressant efficacy of mirtazapine FDT. The new formulation found good acceptance by the patients. The results also suggest a likelihood of improved compliance with the mirtazapine FDT.

Onset of improvement and response to mirtazapine in depression: a multicenter naturalistic study of 4771 patients

The purpose of this open multicenter study of 4771 patients with a DSM-IV diagnosis of Major Depressive Episode was to analyse the response to mirtazapine in general practice and primary care. Patients with a baseline score of at least 20 on the Montgomery-Asberg Depression Rating Scale (MADRS) were treated with mirtazapine for 6 weeks (30 mg/day) and clinically assessed by their psychiatrists at weekly intervals through the MADRS and Clinical Global Improvement (CGI) rating scales. The data analysis was carried out on an "intent-to-treat" basis to collect outcome information on all patients. Our results suggested that the efficacy of the antidepressant effect relates to a nonspecific process. Nearly all patients (95%) showed at least slight improvement at the end of the observation period, while the response to treatment was independent of the clinical forms of depression. In particular, all measures of efficacy displayed the maximum change within the first 2 weeks of treatment, with further improvement occurring at much slower rates. Significant improvement within the first 2 weeks of treatment was highly predictive of the final response, and can serve as a guideline for clinicians when deciding about increased dosage, augmentation, or change of medication in unresponsive patients. Detailed analyses of individual MADRS items showed that mirtazapine's pharmacological profile, unlike selective serotonin reuptake inhibitors, led relatively quickly to a significant reduction of suicidal thoughts, a fact of particular clinical relevance.

Population pharmacokinetic analysis of mirtazapine

OBJECTIVE

Mirtazapine belongs to the new generation of antidepressants that is commonly used in clinical routine. Therefore, we feel it mandatory to control compliance in the context of non-response, adverse events or other clinical situations by means of plasma concentration measurements. While controlled clinical studies have evaluated the effect of individual covariates on the pharmacokinetics of mirtazapine, our analysis aims to identify covariates within a naturalistic clinical setting.

METHODS

We performed non-linear mixed-effects modelling with data from 65 depressed inpatients whose plasma concentrations were measured weekly during their stay in hospital. Each patient's age, height, weight, co-medication, alcohol, coffee and cigarette consumption, weekly serum creatinine concentrations, liver enzyme activity, blood pressure and pulse was noted. From 49 patients, the genotype of cytochrome P450 (CYP) isoenzymes 2D6, 2C9 and 2C19 was analysed.

RESULTS

The clearance of CYP2D6 intermediate metabolisers was reduced by 26% compared with extensive metabolisers. No other factor significantly influenced the clearance of these patients.

CONCLUSION

The variability of mirtazapine plasma concentrations in clinical routine is caused to a relevant degree by CYP2D6. This should be taken into account when therapeutic drug monitoring is carried out to check treatment adherence or when a special clinical situation, such as co-morbidity and add-on medication, demands careful dosing of this drug.

The use of mirtazapine in difficult-to-treat patient populations

Patients who have failed previous antidepressant treatment present substantial clinical management challenges. Similarly, elderly patients require special attention. Three recent studies have shown that mirtazapine has a role to play in the management of these patients. Mirtazapine has proved effective in the treatment of patients who were resistant or intolerant to selective serotonin reuptake inhibitors (SSRIs) and the switch to mirtazapine could be made immediately without the necessity for a taper period. In a double-blind study in patients who were resistant to SSRI treatment, mirtazapine had a more rapid onset of action than sertraline. Mirtazapine has also proved effective in elderly depressed patients and again showed a faster onset of action than another of the SSRIs, paroxetine.

An overview of the clinical efficacy of mirtazapine

Mirtazapine is at least as effective as the tricyclic antidepressants and trazodone in a wide range of patient subgroups including in- and out-patients with moderate to severe depression. It also appears to be at least as effective as the serotonin and noradrenaline reuptake inhibitor venlafaxine in the treatment of severely depressed melancholic patients. When compared with the selective serotonin reuptake inhibitors (SSRIs), mirtazapine shows a significantly earlier onset of action. Further analysis of a study comparing mirtazapine with the SSRI paroxetine indicated that early improvement was a highly sensitive predictor of later stable response for both drugs. The positive predictive value of an early improvement was significantly higher during mirtazapine treatment compared with paroxetine. The negative predictive value approached maximum values as early as week 2 with mirtazapine and week 3 with paroxetine. This suggests that the predictability of the response to treatment is better with mirtazapine than with paroxetine.

Third-generation antidepressants: do they offer advantages over the SSRIs?

Third-generation antidepressants are a group of antidepressant agents of variable action, not confined to serotonin reuptake inhibition. These agents include venlafaxine, reboxetine, nefazodone and mirtazapine. Claims have been made for these agents in terms of improved efficacy, faster speed of onset of effect and greater safety in the treatment of depression compared with previous medications, such as the selective serotonin reuptake inhibitors (SSRIs). This article reviews the evidence for these improvements. Thirty active comparator studies were reviewed involving the third-generation antidepressant agents. While there were isolated reports of improvements over comparator agents for venlafaxine, reboxetine and mirtazepine, there were no convincing differences between third-generation agents and comparators in terms of overall efficacy, relapse prevention and speed of onset. The third-generation antidepressants were, however, of equivalent safety to SSRIs and maintained improvements in safety over first-generation agents.

A review of the pharmacological and clinical profile of mirtazapine

The novel antidepressant mirtazapine has a dual mode of action. It is a noradrenergic and specific serotonergic antidepressant (NaSSA) that acts by antagonizing the adrenergic alpha2-autoreceptors and alpha2-heteroreceptors as well as by blocking 5-HT2 and 5-HT3 receptors. It enhances, therefore, the release of norepinephrine and 5-HT1A-mediated serotonergic transmission. This dual mode of action may conceivably be responsible for mirtazapine's rapid onset of action. Mirtazapine is extensively metabolized in the liver. The cytochrome (CYP) P450 isoenzymes CYP1A2, CYP2D6, and CYP3A4 are mainly responsible for its metabolism. Using once daily dosing, steady-state concentrations are reached after 4 days in adults and 6 days in the elderly. In vitro studies suggest that mirtazapine is unlikely to cause clinically significant drug-drug interactions. Dry mouth, sedation, and increases in appetite and body weight are the most common adverse effects. In contrast to selective serotonin reuptake inhibitors (SSRIs), mirtazapine has no sexual side effects. The antidepressant efficacy of mirtazapine was established in several placebo-controlled trials. In major depression, its efficacy is comparable to that of amitriptyline, clomipramine, doxepin, fluoxetine, paroxetine, citalopram, or venlafaxine. Mirtazapine also appears to be useful in patients suffering from depression comorbid with anxiety symptoms and sleep disturbance. It seems to be safe and effective during long-term use.

Clinical pharmacokinetics of mirtazapine

Mirtazapine is the first noradrenergic and specific serotonergic antidepressant ('NaSSA'). It is rapidly and well absorbed from the gastrointestinal tract after single and multiple oral administration, and peak plasma concentrations are reached within 2 hours. Mirtazapine binds to plasma proteins (85%) in a nonspecific and reversible way. The absolute bioavailability is approximately 50%, mainly because of gut wall and hepatic first-pass metabolism. Mirtazapine shows linear pharmacokinetics over a dose range of 15 to 80mg. The presence of food has a minor effect on the rate, but does not affect the extent, of absorption. The pharmacokinetics of mirtazapine are dependent on gender and age: females and the elderly show higher plasma concentrations than males and young adults. The elimination half-life of mirtazapine ranges from 20 to 40 hours, which is in agreement with the time to reach steady state (4 to 6 days). Total body clearance as determined from intravenous administration to young males amounts to 31 L/h. Liver and moderate renal impairment cause an approximately 30% decrease in oral mirtazapine clearance; severe renal impairment causes a 50% decrease in clearance. There were no clinically or statistically significant differences between poor (PM) and extensive (EM) metabolisers of debrisoquine [a cytochrome P450 (CYP) 2D6 substrate] with regard to the pharmacokinetics of the racemate. The pharmacokinetics of mirtazapine appears to be enantioselective, resulting in higher plasma concentrations and longer half-life of the (R)-(-)-enantiomer (18.0 +/-2.5h) compared with that of the (S)-(+)-enantiomer (9.9+/-3. lh). Genetic CYP2D6 polymorphism has different effects on the enantiomers. For the (R)-(-)-enantiomer there are no differences between EM and PM for any of the kinetic parameters; for (S)-(+)-mirtazapine the area under the concentration-time curve (AUC) is 79% larger in PM than in EM, and a corresponding longer half-life was found. Approximately 100% of the orally administered dose is excreted via urine and faeces within 4 days. Biotransformation is mainly mediated by the CYP2D6 and CYP3A4 isoenzymes. Inhibitors of these isoenzymes, such as paroxetine and fluoxetine, cause modestly increased mirtazapine plasma concentrations (17 and 32%, respectively) without leading to clinically relevant consequences. Enzyme induction by carbamazepine causes a considerable decrease (60%) in mirtazapine plasma concentrations. Mirtazapine has little inhibitory effects on CYP isoenzymes and, therefore, the pharmacokinetics of coadministered drugs are hardly affected by mirtazapine. Although no concentration-effect relationship could be established, it was found that with therapeutic dosages of mirtazapine (15 to 45 mg/day), plasma concentrations range on average from 5 to 100 microg/L.

Mirtazapine: a review of its use in major depression

Mirtazapine is a noradrenergic and specific serotonergic antidepressant (NaSSA) which has predominantly been evaluated in the treatment of major depression. The drug had equivalent efficacy to tricyclic antidepressants and it was at least as effective as trazodone in the majority of available short term trials in patients with moderate or severe depression, including those with baseline anxiety symptoms or sleep disturbance and the elderly. A continuation study also showed that sustained remission rates were higher with mirtazapine than with amitriptyline and that the drugs had similar efficacy for the prevention of relapse. There is some evidence for a faster onset of action with mirtazapine than with the selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors (SSRIs). Mirtazapine was more effective than the SSRI fluoxetine at weeks 3 and 4 of therapy and it was also more effective than paroxetine and citalopram at weeks 1 and 2, respectively, in short term assessments (6 or 8 weeks). Preliminary data suggest that the drug may be effective as an augmentation or combination therapy in patients with refractory depression. Anticholinergic events and other events including tremor and dyspepsia are less common with mirtazapine than with tricyclic antidepressants. There was a greater tendency for SSRI-related adverse events with fluoxetine than with mirtazapine, but, overall, mirtazapine had a similar tolerability profile to the SSRIs. Increased appetite and bodyweight gain appear to be the only events that are reported more often with mirtazapine than with comparator antidepressants. In vitro and in vivo data have suggested that mirtazapine is unlikely to affect the metabolism of drugs metabolised by cytochrome P450 (CYP)2D6, although few formal drug interaction data are available.

CONCLUSIONS

Mirtazapine is effective and well tolerated for the treatment of patients with moderate to severe major depression. Further research is required to define the comparative efficacy of mirtazapine in specific patient groups, including the elderly and those with severe depression. Clarification of its efficacy as an augmentation therapy and in patients with refractory depression and its role in improving the efficacy and reducing the extrapyramidal effects of antipsychotic drugs would also help to establish its clinical value. The low potential for interaction with drugs that are metabolised by CYP2D6, including antipsychotics, tricyclic antidepressants and some SSRIs, may also make mirtazapine an important option for the treatment of major depression in patients who require polytherapy. Mirtazapine also appears to be useful in patients with depression who present with anxiety symptoms and sleep disturbance.

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.

A risk-benefit assessment of mirtazapine in the treatment of depression

Mirtazapine is the first of a new class of antidepressants, the noradrenergic and specific serotonergic antidepressants (NaSSA). Its antidepressant effect appears to be related to its dual enhancement of central noradrenergic and serotonin 5-HT1 receptor-mediated serotonergic neurotransmission. Mirtazapine possesses a number of useful pharmacokinetic characteristics such as good absorption, linear pharmacokinetics over the recommended dosage range (15 to 80 mg/day), and an elimination half-life of 20 to 40 hours, thereby allowing once-daily administration. However, since the drug is extensively metabolised by the hepatic cytochrome P450 (CYP) system and is excreted mainly in the urine, its clearance may be reduced by hepatic or renal impairment. In vitro data suggest that from a clinical point of view it is unlikely that mirtazapine would inhibit the metabolism of coadministered drugs metabolised by CYP1A2, CYP2D6 or CYP3A4. In vivo data from a study in extensive and poor metabolisers of debrisoquine indicate that strong inhibitors of CYP2D6 would have no effect on the concentration of racemic mirtazapine. In some placebo-controlled studies mirtazapine showed an early onset of antidepressant action, with significant reductions in total Hamilton Depression Rating Scale and Montgomery-Asberg Depression Rating Scale scores (relative to placebo) noted as early as 1 week after starting treatment. This therapeutic advantage was subsequently maintained during treatment, with mirtazapine proving significantly superior to placebo at treatment end-point in the majority of studies. In comparative trials, the antidepressant efficacy of mirtazapine was comparable with that of tricyclic antidepressants such as amitriptyline, clomipramine and doxepin, and in 2 studies superior to that of trazodone and fluoxetine. Mirtazapine appears to have a broad spectrum of activity, reflected in its efficacy in a variety of clinical settings. Its additional beneficial effects on the symptoms of anxiety and sleep disturbance associated with depression may reduce the need for concomitant anxiolytic and hypnotic medication seen with some antidepressants. Mirtazapine has demonstrated superior tolerability to the tricyclic antidepressants and trazodone, primarily on account of its relative absence of anticholinergic, adrenergic and serotonin-related adverse effects, in particular gastrointestinal adverse effects and sexual dysfunction. It appears that increased sedation associated with the drug is related to subtherapeutic dosages, and that it is reported in substantially fewer patients when the drug is used in appropriate dosages (> or = 15 mg as a single evening dose) from the beginning of treatment. Although 2 cases of reversible severe symptomatic neutropenia have been reported in clinical trials, there have been no additional reports of symptomatic neutropenia since the introduction of this drug to various countries in September 1994. Currently available data and initial clinical experience suggest that with its combination of dual action, simple pharmacokinetics, and clinical efficacy and tolerability, mirtazapine appears to be an important advance in the pharmacotherapy of depression.

Pharmacological treatment of severely depressed patients: a meta-analysis comparing efficacy of mirtazapine and amitriptyline

Efficacy data were available from 405 severely depressed patients (baseline 17-item Hamilton Rating Scale for Depression-HAMD scores > or = 25) participating in randomized, double-blind, amitriptyline-controlled studies of mirtazapine. Main efficacy variable were changes from baseline in the group mean 17-item HAMD scores and responder rates. Secondary efficacy variables were changes in depressed mood item on the HAMD and in factors derived from the 17-item HAMD scale. Treatment with either mirtazapine or amitriptyline resulted in robust reductions of baseline HAMD scores and in similar and high percentages of responders. Both drugs produced favourable effects on depressed mood and on symptoms commonly associated with depression, such as anxiety, sleep and vegetative disturbances. There were neither statistically significant nor clinically relevant differences between mirtazapine and amitriptyline at any assessment point nor at endpoint. The results demonstrate that the new antidepressant mirtazapine and the tricyclic antidepressant amitriptyline are equally effective in the treatment of severely depressed patients.

Pharmacokinetics of mirtazapine from orally administered tablets: influence of a high-fat meal

The effect of a high-fat meal on the pharmacokinetics of mirtazapine was studied in 19 healthy normal young male volunteers. In a randomized two-period crossover study, each volunteer received an oral dose of 15 mg of mirtazapine in the form of tablets, in the fasting state and after a high-fat meal, with a washout period of 14 days between the two doses. Serial blood samples were taken and pharmacokinetic parameters calculated and statistically analyzed from mirtazapine plasma levels. The extent of absorption of mirtazapine, as measured by the area under the plasma level versus time curve, was found to be equivalent for the fasting and the fed state. Food intake was shown to have no influence on the elimination of mirtazapine, as measured by its elimination half-life. The rate of mirtazapine absorption, as measured by the peak level (Cmax), was not altered by food. The peak time (tmax), however, in subjects in the fed state showed an increase: the 90%-confidence interval for the median difference ranged from 0.25 to 1.25 h. This was the only effect of food found in this study. It is considered to be of no clinical consequence.

Mirtazapine: clinical advantages in the treatment of depression

Mirtazapine is a noradrenergic and specific serotonergic antidepressant, characterized by a unique pharmacologic profile, favorable pharmacokinetics, and proven efficacy and safety. Mirtazapine has demonstrated clinical efficacy in the treatment of moderately and severely depressed patients. In addition, mirtazapine was found to be equally effective as clomipramine in the treatment of severely depressed, hospitalized patients. The overall improvement with mirtazapine is seen after 1 week of treatment and is sustained throughout the treatment period. It is paralleled by an improvement in depressed mood, the core symptom of depressive illness. Because of its unique pharmacologic profile, mirtazapine is virtually devoid of anticholinergic, adrenolytic, and serotonin-related side effects. The most frequently reported adverse events were transient sedation and weight gain.

Meta-analysis of randomized, double-blind, placebo-controlled, efficacy and safety studies of mirtazapine versus amitriptyline in major depression

A meta-analysis was performed on efficacy and safety data from 4 randomized, double-blind, 6-week, single-center studies comparing mirtazapine (n = 194; 5-35 mg/day) with amitriptyline (n = 193, 40-280 mg/day) and placebo (n = 193) in outpatients with a DSM-III diagnosis of major depressive episode. On all the main efficacy variables both active drugs consistently produced significantly greater improvements and significantly greater percentages of responders or remitters than placebo. The meta-analysis of adverse events shows that mirtazapine was better tolerated than amitriptyline, particularly with respect to anticholinergic and cardiac adverse events. There were no differences between mirtazapine and placebo regarding the incidence of serotonergic adverse events. In conclusion, the results of this meta-analysis demonstrate that mirtazapine is as effective as amitriptyline but has a better tolerability profile.