Fatal toxicity of serotoninergic and other antidepressant drugs: analysis of United Kingdom mortality data.

Several studies over the past 15 years have compared the number of fatal poisonings due to antidepressant drugs in the United Kingdom with drug use statistics to derive a fatal toxicity index: deaths per million prescriptions. 2 Greater than 10-fold differences in the index have been shown between tricyclic antidepressants and even larger differences between some tricyclics and newer antidepressants. Explanations have focused on preference for noradrenaline or serotonin reuptake blockade, although only weak correlations have been observed and the explanation is toxicologically implausible. In the late 1990s the use of newer serotoninergic antidepressants increased dramatically. Some data show that venlafaxine in particular may not be as safe in overdose as other serotoninergic drugs, with reports of deaths, arrhythmias, and seizures. We aimed to establish the relative frequency with which venlafaxine and other new antidepressants result in fatal poisoning.