Optimizing antidepressant treatment: efficacy and tolerability

It has been suggested that dual-action antidepressants acting on both serotonin and noradrenaline pathways in the brain may offer superior therapeutic benefit over classical antidepressants, particularly in severe depression. Directly acting dual-action antidepressant drugs include venlafaxine and milnacipran. In addition, mirtazapine and nefazodone, may indirectly potentiate serotonergic and noradrenergic transmission, although evidence that they do indeed do so in vivo is limited. Meta-analysis of clinical trials suggests that venlafaxine has a more rapid onset of action than selective serotonin reuptake inhibitors (SSRIs), and the same may also be true for milnacipran and mirtazapine. Efficacy, both in terms of extent of antidepressant effect and in the proportion of patients responding, is probably superior to that of SSRIs, at least for venlafaxine and milnacipran. In terms of tolerability, all dual-action drugs clearly appear to be better tolerated than tricyclic antidepressants. Mirtazapine and nefazodone have specific side-effect profiles as a result of their antagonist action at biogenic amine and other receptors. Milnacipran, and to a lesser extent venlafaxine, are slightly better tolerated than SSRIs.