Mirtazapine. A pharmacoeconomic review of its use in depression

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 Mirtazapine improved quality of life to a similar extent to fluoxetine, citalopram and paroxetine in unpublished studies of 6 and 8 weeks' duration.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.