Venlafaxine. A review of its pharmacology and therapeutic potential in depression.

Venlafaxine is a phenylethylamine derivative which facilitates neurotransmission in the brain by blocking presynaptic reuptake of serotonin (5-hydroxytryptamine: 5-HT) and noradrenaline (norepinephrine). Clinical data from patients with major depression are consistent with the favourable efficacy and tolerability profile of venlafaxine predicted by pharmacodynamic studies. In patients with major depression, venlafaxine 75 to 375 mg/day administered for 6 weeks was significantly more effective than placebo, and at least as effective as imipramine, clomipramine, trazodone or fluoxetine. Venlafaxine is well tolerated, being associated with fewer anticholinergic and CNS adverse effects than tricyclic antidepressants. Unlike the tricyclic antidepressants, venlafaxine does not appear to significantly affect cardiac conduction, although there have been a few reports of modest increases in blood pressure, particularly after high doses of the drug. In conclusion, wider clinical experience is required to better characterise and confirm potential advantages of venlafaxine compared with other antidepressant agents. These advantages may include a rapid onset of action and reduced propensity to cause anticholinergic effects and cardiotoxicity compared with tricyclic antidepressants. Nevertheless, at this stage venlafaxine offers a more attractive treatment option than tricyclic antidepressants for patients with major depression, primarily because of its good overall tolerability profile.