Paradoxical and severe hypotension in response to adrenaline infusions in massive quetiapine overdose.

Atypical antipsychotics (quetiapine, olanzapine, risperidone and clozapine) are increasingly prescribed in Australia, and emergency departments report growing rates of overdose of these agents. As these drugs are comparatively new, the spectrum of toxicity may be unfamiliar to critical care physicians. Severe hypotension is a recognised consequence of quetiapine poisoning. We describe three patients with massive quetiapine overdose who developed significant hypotension resistant to fluid resuscitation. In each case, blood pressure fell dramatically after commencement of adrenaline infusions. Haemodynamic stability was restored when noradrenaline was substituted for adrenaline. The pharmacodynamics of quetiapine and the literature on overdose are reviewed. We present these cases to broaden the knowledge of physicians treating quetiapine overdose and to publicise the potential deleterious interaction with adrenaline. We recommend use of noradrenaline in preference to adrenaline in pharmacological management of shock in these patients. (author abstract)