Venlafaxine therapeutic efficacy

Augmentation, i.e. the addition of another drug, is used to enhance the effects of standard antidepressants when two or more have successively failed to alleviate depressive symptoms despite treatment at an adequate dose for an adequate time. The therapeutic efficacy of new agents, e.g. venlafaxine, has provided clinicians with further options which now tend to be employed before augmentation but the following may be used. 

Several findings support the view that antidepressants that enhance both serotonin and norepinephrine (dual-acting antidepressants) have greater therapeutic efficacy compared with antidepressants that enhance either neurotransmitter alone (e.g. SSRIs enhance mainly serotonin, while reboxetine and desipramine enhance predominantly norepinephrine). It is specifically proposed that the dual-acting SNRIs may display faster onset of action and can be more efficacious in cases of severe depression. There are four new-generation dual-acting antidepressants duloxetine, milnacipran, mirtazapine, and venlafaxine. ... 

A critical review by Olver et al. (2001) on so-called third-generation antidepressants (venlafaxine, reboxetine, nefazodone, mirtazapine) covered 30 controlled therapeutic trials and a number of relapse prevention studies. Questions addressed were overall efficacy, speed of onset and safety but, according to this review, none of the third-generation antidepressants was specifically tested with respect to its potential effects on cognitive function in depressed patients. 

Although the efficacy of tricyclic antidepressants in the treatment of unipolar depression is beyond reproach, the side-effect profile of these agents makes them less desirable as first-line therapeutic agents. Introduction of selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine, paroxetine, sertraline, citalopram and fluvoxamine in the past decade has revolutionized the treatment of depression universally. The side-effect profile of SSRIs, such as nausea, diarrhea and sexual dysfunction, is considerably more benign than that of tricyclic drugs. Multiple controlled trials have proven the efficacy of SSRIs vs. placebo (Nemeroff, 1994). Recently, a number of SNRIs (serotonin and noradrenaline reuptake inhibitors) and so-called atypical antidepressants have been marketed that may have additional advantages over SSRIs, such as more rapid onset of action (venlafaxine. mirtazapine) and low sexual side-effect potential ( bupropion, nefazodone). Additionally, it appears that venlafaxine may be more efficacious in cases of treatment-refractory depression (Clerc et al., 1994 Fatemi et al., 1999). Finally, in a recent report (Thase et al., 2001),... 

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