Mirtazapine. A pharmacoeconomic review of its use in depression.

UNLABELLED: Mirtazapine is a noradrenergic and specific serotonergic antidepressant (NaSSA). The antidepressant efficacy of mirtazapine has been established in randomised, double-blind comparative studies. Mirtazapine has generally shown similar efficacy to other antidepressants. There is evidence for a faster onset of action with mirtazapine than with the selective serotonin (5-hydroxytryptamine; 5-HT) re-uptake inhibitors (SSRIs) on the basis of mean depression rating scale scores. Data from a long term (mean 240 days) clinical trial that was subsequently used in pharmacoeconomic analyses showed that mirtazapine was associated with significantly higher sustained remission rates and rates of discontinuation because of improvement than amitriptyline and placebo. Although differences were not statistically significant, mirtazapine had higher response rates at 6 weeks than the SSRI fluoxetine in an analysis that was also used as the basis of pharmacoeconomic studies. Mirtazapine improved quality of life to a similar extent to fluoxetine, citalopram and paroxetine in unpublished studies of 6 and 8 weeks' duration. Pooled analyses suggest that mirtazapine may be associated with greater improvement than fluoxetine and citalopram in quality of life after 2 and 4 weeks, although confirmation is required. In a decision analytical model of approximately 6 months' duration, mirtazapine was associated with a higher proportion of successfully treated patients and lower total direct costs than amitriptyline. The direct cost per successfully treated patient with mirtazapine was lower than that with amitriptyline by 33,112 Austrian schillings (S; year of costing not stated), 24,212 French francs (FF; 1995/1996 values), 13,851 Swedish kronor (SEK; 1997 values) and 553 Pounds (1997/1998 values) in Austrian, French, Swedish and UK analyses, respectively. Compared with fluoxetine, mirtazapine was associated with higher per-patient costs in all 4 countries but a higher proportion of successfully treated patients. Mirtazapine was more cost effective than fluoxetine: the direct cost per successfully treated patient was lower by S32,046 in Austria, FF25,914 in France, SEK9796 in Sweden and 327 Pounds in the UK. The additional cost of mirtazapine versus fluoxetine for each additional successfully treated patient at 6 months was S11,732, SEK17,229, 750 Pounds and FF3342 in the Austrian, Swedish, UK and French analyses, respectively. Mirtazapine was generally associated with lower indirect costs (for lost productivity of employed patients) than amitriptyline and similar indirect costs to fluoxetine in the analyses. CONCLUSIONS: Available data suggest that mirtazapine is a cost-effective alternative to amitriptyline and fluoxetine for the treatment of depression. Mirtazapine also has similar effects to SSRIs on quality of life with possibly a shorter time to onset of action, although published trial results are required to confirm these preliminary data.

Zolpidem: an update of its pharmacology, therapeutic efficacy and tolerability in the treatment of insomnia.

UNLABELLED: Zolpidem is an imidazopyridine agent that is indicated for the short term (< or = 4 weeks) treatment of insomnia (recommended dosage 10 mg/day in adults and 5 or 10 mg/day in the elderly or patients with hepatic impairment). Data have shown that the hypnotic efficacy of zolpidem is generally comparable to that of the benzodiazepines flunitrazepam, flurazepam, nitrazepam, temazepam and triazolam as well as nonbenzodiazepine hypnotic agents such as zopiclone and trazodone in the treatment of elderly and adult patients with insomnia. The comparative efficacy of a recently available nonbenzodiazepine hypnotic zaleplon and zolpidem has yet to be established. There was no evidence of tolerance developing to the hypnotic effects of zolpidem in a number of studies of up to 6 months' duration. However, tolerance has been described in a few patients taking the drug at high dosages for periods of up to several years. Zolpidem is well tolerated in patients with insomnia and the most common adverse events are generally nausea, dizziness and drowsiness. Although zolpidem produced some psychomotor and memory impairment over the first few hours after administration, it had few next-day effects (including effects on daytime well-being and morning coordination). In this respect, it was comparable or superior to flunitrazepam and flurazepam and comparable to other benzodiazepines in patients with insomnia. Zolpidem appears to have a low potential for abuse. CONCLUSIONS: Zolpidem is effective and well tolerated in patients with insomnia, including the elderly. Studies have shown that zolpidem generally has similar efficacy to other hypnotics including benzodiazepines and zopiclone. Zolpidem appears to have minimal next-day effects on cognition and psychomotor performance when administered at bedtime. In addition, there is little evidence of tolerance to the hypnotic effects of zolpidem, or rebound insomnia or withdrawal symptoms after discontinuation of the drug when it is given as recommended (10 mg/day for < 1 month) or over longer periods.

Bupropion: a review of its use in the management of smoking cessation.

UNLABELLED: Sustained release bupropion (amfebutamone) is a non-nicotine agent that is indicated as an aid to smoking cessation. In 2 large well designed clinical trials, sustained release bupropion 300 mg/day (the recommended dose) for 7 or 9 weeks was associated with considerably and significantly higher smoking abstinence rates (continuous abstinence and 7-day point prevalence rates) than placebo during treatment and at follow-up at 6 and 12 months. Point prevalence rates at 12 months in 2 studies were 23.1 and 30.3% with bupropion, whereas values for placebo were 12.4 and 15.6%. Continuous abstinence rates at 12 months, available from 1 trial, were 18.4% with bupropion and 5.6% with placebo. Furthermore, bupropion was associated with significantly higher quitting rates than nicotine patch in a comparative study. Combination therapy with bupropion and nicotine patch provided slightly higher abstinence rates than bupropion alone, although differences were not statistically significant. The combination was superior to nicotine patch alone. Data from a preliminary report of long term bupropion treatment (52 weeks) showed that the drug was associated with significantly higher continuous abstinence rates than placebo only to 6 months. However, point prevalence abstinence rates were significantly higher with bupropion than placebo to 18 months. Bupropion 300 mg/day recipients reported nicotine withdrawal symptoms during treatment; however, the symptoms were significantly less severe with bupropion than placebo. Patients receiving bupropion 300 mg/day or bupropion in combination with nicotine patch for smoking cessation generally gained less bodyweight than placebo recipients. The benefits of bupropion for preventing weight gain persisted after the completion of long term, but not short term therapy. Bupropion was well tolerated in clinical trials, and the only adverse events that were significantly more common with bupropion than placebo were insomnia and dry mouth. Data published so far suggest that sustained release bupropion has a low potential for inducing seizures (seizure rate approximately 0.1% in patients with depression). CONCLUSIONS: Bupropion is an effective and well tolerated smoking cessation intervention. Further studies with long term follow-up will be useful in determining whether abstinence rates are maintained with bupropion. In addition, clarification of its efficacy in comparison with other therapies used for smoking cessation would help to establish its clinical value. The reduced potential for weight gain with bupropion and the ability to use bupropion in combination with nicotine replacement therapy make the drug a useful treatment option for smoking cessation.

Entacapone. A review of its use in Parkinson's disease.

UNLABELLED: Entacapone is a potent and specific peripheral catechol-O-methyltransferase (COMT) inhibitor. It has been shown to improve the clinical benefits of levodopa plus an aromatic L-amino acid decarboxylase inhibitor (AADC) when given to patients with Parkinson's disease and end-of-dose deterioration in the response to levodopa (the 'wearing off' phenomenon). The efficacy of entacapone is currently being assessed in patients with stable Parkinson's disease. In 2 well conducted trials of 6 months' duration and smaller short term studies, treatment with entacapone (200 mg with each dose of levodopa/AADC inhibitor) was associated with significant increases in daily 'on' time and decreases in 'off' time. Changes in Unified Parkinson's Disease Rating Scale (UPDRS) scores concurred with changes in 'on' and 'off' times: entacapone improved total, activities of daily living and motor function scores, but it had no effect on mentation scores. Entacapone also provided benefits when given with controlled release levodopa/ AADC inhibitor or with standard levodopa/AADC inhibitor and selegiline in small trials. Dopaminergic events, including dyskinesia and nausea, are among the most common events with entacapone, and are related to the drug's ability to potentiate the effects of levodopa. Diarrhoea, abdominal pain, constipation and urine discolouration are the most common nondopaminergic events, although the latter event is the only one to occur consistently more frequently with entacapone than with placebo. However, adverse events of any type infrequently led to study discontinuation. CONCLUSIONS: The efficacy and tolerability of entacapone administered with levodopa/AADC inhibitor have not yet been compared with those of other strategies for the treatment of Parkinson's disease. However, once the decision to initiate levodopa therapy has been made, studies generally support the use of entacapone as an adjunct to levodopa in patients with Parkinson's disease and the 'wearing off' phenomenon.

Mirtazapine: a review of its use in major depression.

UNLABELLED: 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.

Liposomal influenza vaccine.

This trivalent liposomal influenza vaccine consists of purified influenza haemagglutinin inserted into a membrane of phosphatidylcholine and phosphatidylethanolamine. It contains 15microg of haemagglutinin per viral strain per dose. The vaccine is immunogenic in the elderly, in younger adults and in children and adolescents with or without cystic fibrosis. Seroconversion rates were significantly higher with the liposomal vaccine than with a subunit vaccine for 3 of 3 and 2 of 3 strains in 2 published studies. Seroconversion occurred in a significantly greater number of participants receiving the liposomal vaccine than in those receiving a whole virus vaccine for all 3 strains in 1 study. Seroprotection rates were significantly better with the liposomal vaccine than with a subunit vaccine for 2 of 3 and 1 of 3 strains in 2 trials, and greater than with a whole virus vaccine for 2 of 3 strains in 1 trial. In a study in children with cystic fibrosis, a single dose of the liposomal vaccine was reported to have greater immunogenicity than 2 half doses (statistical analysis not performed). Local adverse reactions such as pain at the injection site, local induration, redness and swelling are transient and usually mild. Liposomal influenza vaccine did not induce a mean antiphospholipid antibody response in elderly volunteers.