Benzodiazepine-associated atrioventricular block

Anna M. Arroyo Plasencia, Lynn M. Ballentine, James B. Mowry, Louise W. Kao

Research output: Contribution to journalArticle

9 Scopus citations


Dysrhythmias, although common in overdose situations, are not often seen after benzodiazepine exposures. We report two cases of transient atrioventricular block after benzodiazepine misuse. Case 1 is a 4-year-old boy who was found unresponsive after an ingestion of clonazepam. An electrocardiogram (EKG) performed on emergency department presentation demonstrated first-degree atrioventricular block (PR 206 ms). After flumazenil administration, he developed second-degree atrioventricular block (Mobitz Type 1). EKG abnormalities resolved by morning. Serum clonazepam was 478 ng/mL (laboratory clonazepam reference range, 10-75 ng/mL with a dose of up to 6 mg/day) 5 hours after being found unresponsive. Case 2 is a 23-year-old man who presented to the emergency department after ingesting risperidone, combination hydrocodone/acetaminophen, and alprazolam. On arrival, his EKG demonstrated sinus bradycardia with a PR interval of 182 msec. He subsequently developed second-degree atrioventricular block (Mobitz Type I). Sinus bradycardia with resolution of his atrioventricular block (PR 200 ms) was seen on a third EKG performed 5 hours after presentation. These two patients demonstrated transient first-and second-degree atrioventricular block after benzodiazepine exposure. Benzodiazepines have been shown to alter L-type Ca2+ channel function. This alteration in function may account for the dysrhythmias seen in our patients. Together, these cases serve to remind clinicians of this rare but potentially serious complication associated with benzodiazepine exposure.

Original languageEnglish (US)
Pages (from-to)e48-e52
JournalAmerican journal of therapeutics
Issue number1
StatePublished - Jan 1 2012


  • alprazolam
  • clonazepam
  • dysrhythmia
  • flumazenil
  • heart block

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)

Fingerprint Dive into the research topics of 'Benzodiazepine-associated atrioventricular block'. Together they form a unique fingerprint.

  • Cite this