Comparison of some effects of paroxetine with amitriptyline on the cardiovascular system in animals

The effects of intravenous infusions of paroxetine, a novel inhibitor of 5-hydroxytryptamine (5HT) uptake, and of the tricyclic antidepressant, amitriptyline, on the cardiovascular system have been compared in the conscious rabbit and in the anaesthetised cat. As judged by the dose required to produce changes in ECG waveform (including PR and QTc intervals) and disorders of heart rhythm, paroxetine was less cardiotoxic than amitriptyline in both species. Thus, paroxetine has the advantage over amitriptyline of being less toxic to the cardiovascular system which could constitute a considerable advantage in clinical use particularly as other work has shown it to be more potent than amitriptyline in tests for antidepressant activity.