Case #16: To Grandma’s Medicine Cabinet We Go
Author: Erin Clark, MD
Peer Reviewer: Christopher Hoyte, MD
An 18 year old female with a history of two prior suicide attempts is brought to the ED by EMS. She is somnolent, but arousable. Her mother comes to the ED and reports the patient had been at her grandmother’s that day. Her grandmother has a history of multiple medical problems and reports that it looks like some of the pill bottles are missing from her medicine cabinet.
Vitals: Temp: 98.6, HR: 42, RR: 14, BP: 90/50, O2 Sat: 100% on RA
The patient’s mother goes to the grandmother’s house and comes back reporting that the grandmother is only missing her bottle of metoprolol.
What clinical presentations might you expect to see with this drug?
General: Hypothermia
CNS: AMS, Coma, Respiratory arrest
Cardiovascular: Bradycardia, Hypotension
Pulmonary: Bronchospasm (COPD/asthma)
Metabolic: Hypoglycemia, Hyperkalemia
What is the most dangerous beta blocker?
Propranolol is the most dangerous beta blocker. It is both a combined beta 1 and 2 blocker, as well as a Na channel blocker. It can also cross the blood brain barrier and cause seizures.
Note: Beware of Sotalol (Class III antiarrhythmic), which can prolong the QT interval, leading to Torsades de Pointes.
How can one differentiate beta blocker overdose from calcium channel blocker overdose and clonidine overdose?
Differentiating between these overdoses can be difficult. Calcium channel blocker overdose is often associated with hyperglycemia. Clonidine overdose can mimic opioid intoxication with decreased respirations, miosis, and somnolence.
Over what time period do patients usually exhibit symptoms of overdose?
Absorption of regular-release (i.e. not sustained-release) preparations usually occurs within one to four hours. Sustained-release preparation ingestions may not show symptoms for up to six hours. Co-ingestants that alter absorption, such as opiates and anticholinergics, may delay the onset of symptoms.
What is the initial management and treatment?
Initial management includes, as always, managing the ABCs.
Gastric decontamination may be considered if the patient is awake, alert, and has taken a large ingestion within one hour of presentation. The patient should be aggressively hydrated with
intravenous fluids. Vasopressors may be required.
Glucagon 5-10 mg IV is considered the first line therapy for overdose. It works directly on the heart by bypassing the beta receptor and directly activating adenylate cyclase, thereby raising the heart rate. High dose insulin (1 Unit/kg/hour) may also be considered (see below). Atropine is often ineffective.
How effective is high dose insulin for beat-blocker overdose?
High-dose insulin therapy is highly recommended for calcium channel blocker overdose and has recently received a lot of attention for beta-blocker overdose. Much of the initial support for beta-blocker overdose came from animal studies. However, human trials show little actual benefit with the exception of propranolol overdose.
Suppose the patient had taken a calcium channel blocker instead. Are there any new treatments for calcium channel blocker overdose?
High-dose insulin therapy has emerged as an effective treatment for calcium channel blocker overdose. Several mechanisms as to how this therapy works have been proposed: namely, increased inotropy, increased intracellular glucose transport, and vascular dilatation. The current recommended dosage is a
1 unit/kg bolus followed by
1-10 unit/kg/hour continuous infusion.
Intravenous lipid emulsion therapy has also shown promise. The typical dose is a bolus of 100 mg which can be repeated every 5-10 minutes for at least 3 doses.
References:
Benowitz, NL. Chapter 32. Beta-Adrenergic Blockers. In: Olson, KR, Poisoning & Drug Overdose. 6th Ed. New York: McGraw-Hill; 2012
DeWitt CR, Waksman JC. Pharmacology, pathophysiology, and management of calcium channel blocker and beta-blocker toxicity. Toxicol Rev. 2004;23(4):223-38.
Engebretsen KM, Kaczmarek KM, Morgan J, et al. High-dose insulin therapy in beta-blocker and calcium channel-blocker poisoning. Clin Toxicol (Phila). 2011 Apr;49(4):277-83.
Love JN, Enlow B, Howell JM, et al. Electrocardigraphic changes associated with beta-blocker toxicity. Ann Emerg Med. 2002 Dec;40(6):603-10.
Patel NP, Pugh ME, Goldberg S, et al. Hyperinsulinemic euglycemia therapy for verapamil poisoning: a review. Am J Crit Care. 2007 Sep;16(5):498-503.
Shepherd G. Treatment of poisoning caused by beta-adrenergic and calcium-channel blockers. Am J Health Syst Pharm. 2006 Oct 1;63(19):1828-35.
Tomaszewski, CA. Chapter 40. Calcium Channel Antagonists. In: Olson, KR, Poisoning & Drug Overdose. 6th Ed. New York: McGraw-Hill; 2012
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