THE FORGOTTEN TRUTH ABOUT COMMON COLD FORMULATIONS’ POTENTIAL TO CAUSE WIDE COMPLEX TACHYCARDIA AND SEIZURES

Abstract

SESSION TITLE: Medical Student/Resident Cardiovascular Disease Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: First-generation antihistamines: diphenhydramine and doxylamine are readily available over the counter medications. These drugs are commonly used as sleep aids, cold, and allergy medications due to their anticholinergic and anti-histamine effects. Here we present a 19-year-old female, who presented to the hospital after an intentional overdose of over the counter cold medications. This case serves to remind us of the potential for life-threatening arrhythmias associated with these medications. CASE PRESENTATION: We present a 19-year-old-year-old female with a past medical history of depression, dissociative identity disorder, and multiple suicide attempts who called EMS after reporting an intentional overdose of unknown quantities of Nyquil, Unisom, and Benadryl. Daily Ativan was her only home medication. En route to the hospital, she had two witnessed tonic-clonic seizures, which resolved after two doses of Ativan. On admission, she was alert but irritable, easily startled, and confused. She had no cardiac or respiratory symptoms. Vital signs were stable except for heart rates in the 160s. Initial EKG showed a wide complex tachycardia, a left bundle branch block and left axis deviation. Troponins were negative. She was given a dose of physostigmine, several bicarbonate pushes, and eventually started on a sodium bicarbonate infusion. Due to worsening mental status and upper extremity myoclonic jerks concerning for ongoing seizures, she was intubated for airway protection. After 5 hours of sodium bicarbonate infusion, the wide complex tachycardia resolved. During her 10-day hospital stay, she developed hypokalemia and metabolic alkalosis, which resolved after potassium supplementation and cessation of bicarbonate infusion respectively. In addition, she developed rhabdomyolysis and lactic acidosis both of which resolved after fluid resuscitation. The patient continued to have intermittent myoclonic jerks and new vertical nystagmus. EEG did not show seizure activity. Her mental status returned to baseline. EKG remained in normal sinus rhythm and she was finally discharged with close psychiatry follow up. DISCUSSION: We present a patient who overdosed on first-generation anti-histamines resulting in a wide complex tachyarrhythmia and seizures. Cardiac arrhythmias develop due to increased excitability, slowed conduction of the fast inward sodium current as well as QT interval prolongation. Antagonism at the H1 receptor mediates seizure activity. Management should be focused on early pattern recognition, sodium bicarbonate, and anti-epileptic therapy. CONCLUSIONS: Although widely used and easily available, over the counter formulations are an increasingly rare but possible cause of life-threatening arrhythmias and seizures if taken in large amounts. It is imperative that patients be educated on the potential side effects of these commonly prescribed medications. Reference #1: Joshi, Ajay K., et al. “Case of Polymorphic Ventricular Tachycardia in Diphenhydramine Poisoning.” Journal of Cardiovascular Electrophysiology, vol. 15, no. 5, 2004, pp. 591–593., doi:10.1046/j.1540-8167.2004.03173.x Reference #2: Su, Mark, and Matthew Goldman . “Anticholinergic Poisoning.” UpToDate, 2019, www.uptodate.com/contents/tricyclic-antidepressant-poisoning?topicRef=305&source=see_link#H15. DISCLOSURES: No relevant relationships by Andre Gabriel, source=Web Response No relevant relationships by Jasmin Hundal, source=Web Response No relevant relationships by Brenda Nyatanga, source=Web Response