Paradoxical refractory hypotension following adrenaline administration in a patient taking clozapine

Clozapine is a potent antipsychotic commonly used for refractory schizophrenia. Adverse effects are well recognised including constipation, intestinal obstruction, agranulocytosis and cardiomyopathy. We present a case of paradoxical refractory hypotension following epinephrine administration in a patient taking clozapine. A psychiatric inpatient who had been taking clozapine for many years developed paralytic ileus and obstruction requiring surgical intervention. Following initiation of epinephrine administration intraoperatively he developed refractory hypotension which improved only when epinephrine was weaned off. This effect is likely due to uninterrupted β₂-agonist activity in the presence of clozapine-induced α-blockade. Clinicians need to have greater awareness of this serious interaction and avoid the use of epinephrine in patients taking clozapine.