Venlafaxine: more dangerous than most "selective" serotonergic antidepressants

Venlafaxine is a serotonergic and noradrenergic antidepressant. It shares the same serotonergic adverse effects as the "selective" serotonin reuptake inhibitor (SSRI) antidepressants while in addition provoking noradrenergic adverse effects, in particular cardiovascular disorders, yet offers no demonstrated advantages over SSRIs in terms of efficacy. Several cohort studies using data from a UK database have shown that venlafaxine overdoses are more frequently fatal than SSRI overdoses. Several meta-analyses of more than 70 published and unpublished randomised clinical trials, including about 7000 patients in total, have shown that treatment discontinuation due to adverse effects is more common with venlafaxine than with SSRI antidepressants. Venlafaxine can provoke dose-dependent blood pressure elevation, sometimes requiring treatment discontinuation. Exposure to venlafaxine during the second and third trimesters of pregnancy increases the risk of pre-eclampsia and eclampsia. A cohort study in about 50 elderly patients and analysis of several hundred reported suicide attempts by venlafaxine overdose demonstrated a risk of QT interval prolongation, which can lead to torsades de pointes, an unusual and potentially fatal type of ventricular tachycardia. Large British and Danish cohort studies found no increased risk of sudden cardiac death with venlafaxine compared with other antidepressants. However, since only 3.5% and 7% of the patients were using venlafaxine, the statistical power of these studies was relatively low. In practice, the data available as of mid-2015 from clinical trials and epidemiological studies confirm the harms foreseeable from venlafaxine's pharmacological properties: a higher risk of cardiovascular adverse effects and of fatal overdoses than with most SSRI antidepressants. Since venlafaxine and SSRI antidepressants have similar and limited efficacy, venlafaxine is best avoided. An SSRI anti-depressant is a more reasonable option, with the exception of citalopram and escitalopram which also expose patients to more cardiovascular adverse effects.