Clozapine Induced Hypertension and its Association with Autonomic Dysfunction

Clozapine is a second generation antipsychotic agent which is drug of choice for treatment resistant schizophrenia. Tachycardia and postural hypotension are most frequently observed cardiovascular adverse effects, but reports on new-onset persistently elevated blood pressure are sparse. Mechanisms underlying clozapine induced hypertension also remain unclear. We report the case of a 32 year old normotensive male with persistently elevated systolic and diastolic blood pressure after clozapine initiation. Hypertension persisted throughout the phase of dose optimization and dose stabilization at 300 mg/day, requiring an addition of a beta blocker (atenolol) after a month of observation. The 24 hour urinary catecholamines were within normal limits. Autonomic function tests revealed severe loss of parasympathetic activity and cardiac autonomic tone. The case adds to limited information on autonomic dysfunction as a potential factor in clozapine induced hypertension.