In the first study to compare the efficacy and tolerability of mirtazapine(Drug information on mirtazapine) (Remeron) and fluoxetine(Drug information on fluoxetine) (Prozac) in patients with major depression, David Wheatley, M.D., of The Royal Masonic Hospital, London, and colleagues from throughout Europe showed mirtazapine and fluoxetine to be similar in tolerability, with mirtazapine significantly superior in efficacy.
The multicenter, randomized, double-blind comparison was performed in 22 centers throughout Europe between August 1994 and March 1996. The study comprised male and female inpatients and outpatients between the ages of 18 and 75 who fulfilled the DSM-III-R criteria for a major depressive episode. The 133 patients were randomly assigned to either mirtazapine (N=66) 15-60 mg/day; or fluoxetine (N=67) 20-40 mg/day.
At the end of the study, Wheatley and colleagues found that reductions from baseline in group mean 17-HAM-D scores were evident in both treatment groups throughout the study period. The difference between the mirtazapine-treated group compared to the fluoxetine group reached statistical significance days 21 and 28. Decreases from baseline in depressed mood item scores were also evident in both groups with more decreases in the mirtazapine group, reaching a statistically significant difference at day 28.
The incidence of adverse events was reported by 10% of patients. Common complaints were headache and nausea (fluoxetine), and dry mouth and blurred vision (mirtazapine). Blood pressure and heart rate measurement remained within safety limits for both treatment groups.
Investigators report that the difference in efficacy of the two drugs was similar to that seen between an efficacious antidepressant drug and placebo. However, the fact that the study was lacking a placebo arm should be taken into account when interpreting results. They also cautioned that mirtazapine is more rapidly effective than fluoxetine, and that a longer duration of study (e.g., eight weeks) with a design specifically addressing onset of response would resolve this issue. In addition, researchers said, the small size of the study may have made it difficult to detect subtle differences in tolerability profiles-MB
