A case of sinus pause induced by swallowing in the setting of olanzapine and guanfacine overdose

Abstract

Olanzapine, a second-generation antipsychotic, is used in both adult and pediatric populations for schizophrenia, bipolar disorder, and depression and has been associated with autonomic dysregulation in the setting of overdose. Guanfacine is a sympatholytic drug used in the treatment of attention deficit hyperactivity disorder and has also been associated with autonomic dysfunction. We present a unique case of a 17-year-old male who overdosed on 340 mg of olanzapine and 189 mg of extended-release guanfacine with a previously unreported adverse event. Specifically, five days after ingestion, he developed a 5–8 s sinus pause every time he forcefully swallowed any beverage, suggestive of a vagal hypersensitivity reaction. The report will review the autonomic dysfunction of olanzapine and guanfacine and management of asymptomatic sinus pause in the critical care setting.