A Case of Prolonged Bradycardia and Hypotension After Ingestion of Incorrect Guanfacine Formulation

Guanfacine is an alpha-two agonist commonly manufactured in two formulations, an extended-release formulation primarily used for the treatment of attention-deficit hyperactivity disorder (ADHD) in the pediatric population, and an instant-release formulation primarily used for the treatment of hypertension in the adult population. Formulation errors can cause profound adverse effects, especially given the different intended uses for each patient population. We present the case of a six-year-old male who was mistakenly prescribed 2 mg of instant-release guanfacine as opposed to his usual 2 mg of extended-release guanfacine. He presented to the emergency department (ED) with lethargy, bradycardia, hypotension and eventually required initiation of vasopressors. He was admitted to the pediatric intensive care unit (PICU) due to hemodynamic instability, where he metabolized the ingestion and clinically improved over the subsequent 34 hours. This case was unique as it demonstrates a profound alteration in hemodynamics after a seemingly small medication error, which is not often reported for this medication. This case report also demonstrates the importance of recognizing specific medication formulations and highlights the need for careful medication prescribing and dispensing.