Clonidine Compounding Error: Bradycardia and Sedation in a Pediatric Patient

Clonidine is a centrally-acting α-2 agonist used in the treatment of hypertension and attention-deficit/hyperactivity disorder, among other off-label uses. In overdose, it can cause sedation, bradycardia, and hypotension. Clonidine can be compounded as a liquid formula for patients who are unable to take pills, however, this can add to the risk of dosing errors.

A 12-year-old boy diagnosed with autism, prescribed buspirone and clonidine, presented to the emergency department for altered mental status. His examination revealed generalized sedation, bradycardia (heart rate 30-40 beats/min), and hypotension (blood pressure 82/48 mm Hg). Resuscitation included i.v. crystalloids and multiple doses of atropine. Over the next 24 h, his vital signs and mental status normalized. He displayed no infectious symptoms or focal neurologic deficits. His parents noted that his medications had been refilled recently at the compounding pharmacy; because he was unable to take pills, his medications were in liquid formulation. Because his signs and symptoms were suspicious for a central α-2 agonist overdose, his clonidine preparation was sent to a reference laboratory for analysis. This analysis revealed the concentration was approximately eight times higher than indicated on its label. WHY SHOULD AND EMERGENCY PHYSICIAN BE AWARE OF THIS?: Compounding pharmacy errors can be a source of toxicity, even if there is no known history of an overdose. Recognizing the toxidrome of sedation, respiratory depression, bradycardia, hypotension, and miosis will lead to appropriate treatment of the patient and should prompt an investigation of the medication error to prevent further harm.