NEW YORK (Reuters Health) – Results of an updated meta-analysis indicate that there are no clinically relevant differences in efficacy or effectiveness among second-generation antidepressants used to treat any of the phases of major depressive disorder.

“Current evidence does not warrant recommending a particular second-generation antidepressant on the basis of differences in efficacy,” conclude the authors of the report in the Annals of Internal Medicine for December 5. However, they add, “Differences in onset of action and adverse events may be considered when choosing a medication.”

Dr. Gerald Gartlehner, at Danube University in Krems, Austria, and colleagues point out that neurotransmitter-targeted antidepressants such as selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors account for most prescriptions for treating major depressive disorder.

Recent reviews of the comparative effectiveness of these agents have reached contradictory conclusions, however. To clarify the situation, the team identified 3927 studies involving any of the 13 second-generation antidepressants available in the US (bupropion, citalopram, desvenlafaxine, duloxetine, escitalopram, fluoxetine, fluvoxamine, mirtazapine, nefazodone, paroxetine, sertraline, trazodone, and venlafaxine).

Among these studies, 234 reports of either randomized trials of at least 6 weeks’ duration or observational studies with at least 1000 participants were considered to be of good or fair quality and were included in the meta-analysis.

While there were statistical differences in response rates between various drugs, the investigators found that, overall, there were no substantial differences in outcomes in the acute, continuation, or maintenance phase of major depressive disorder. This held true for subgroups stratified by age, sex, ethnicity and comorbidity, Dr. Gartlehner and colleagues report.

However, they comment, “Although second-generation antidepressants are similar in efficacy, they cannot be considered identical drugs.” That’s because of differences in time to onset of action between different drugs, as well as adverse-event profiles and some aspects of quality of life.

“For example, mirtazapine has a faster onset of action than citalopram, fluoxetine, paroxetine, and sertraline, whereas bupropion has fewer sexual side effects than escitalopram, fluoxetine, paroxetine, and sertraline,” the authors point out.

They suggest these differences may be considered in choosing an antidepressant for a specific patient, and they advise: “Given the difficulty in predicting what medication will be both efficacious for and tolerated by an individual patient, familiarity with a broad spectrum of antidepressants is prudent.”

Reference:

Ann Intern Med 2011;155:772-785.