This patient presents to the Emergency department with generalized weakness and dizziness after accidently ingesting extra diltiazem tablets 1.5 hours prior to arrival.  The exam shows bradycardia, hypotension, an elevated glucose level, and a patient without altered mental status.  The EKG shows sinus bradycardia without any conduction blocks.

This patient’s clinical presentation is likely due to diltiazem overdose.  Diltiazem is a calcium channel blocker. Calcium channel blocker medications are categorized as the dihydropyridines (nifedipine, amlodipine, nicardipine) and the non-dihydropyridines (verapamil, diltiazem).  The dihydropyridines (DHPs) cause systemic vasodilation, hypotension, and often a reflex tachycardia in overdose.  The non-DHPs act more directly on the heart with less peripheral effects and cause hypotension and bradycardia.  Calcium channel blocker overdose can mimic beta blocker overdose as both medication classes have similar effects on the body. 

The initial management of any patient who has ingested a potentially dangerous medication is the “ABCs”, also known as the primary survey.  This includes assessment and management of the airway (i.e., intubation for somnolence and aspiration risk), breathing (i.e., supplemental oxygen for hypoxia), and circulation (i.e., IV fluids, vasopressors for hypotension).  Decontamination is another consideration depending on the agent the patient has been exposed to.  An EKG should be ordered early in all toxic ingestions to evaluate for signs of cardiac toxicity, such as a prolonged QT interval or prolonged QRS interval.  Checking for other dangerous coingestants, like serum levels of salicylates and paracetamol (APAP) should be routinely done.  Specific toxic effects seen in calcium channel blocker and beta blocker overdose are outlined in the chart below.

IV Glucagon (Choice A) is useful as an adjunctive treatment in both calcium channel blocker and beta blocker overdose.  However, glucagon often causes vomiting and is not a first-line agent.  IV fluids, atropine, vasopressors, and activated charcoal should be attempted before glucagon.  Antiemetics should be considered prior to IV Glucagon administration given its side effect of nausea and vomiting.  Transvenous pacing (Choice C) and IV Calcium gluconate (Choice D) are also considered second-line treatments to try when the patient is not responding to IV fluids, atropine, or vasopressors.  The best next step in this case is to administer IV Fluids (Choice B). 

This patient arrives to the Emergency department with altered mental status and hypotension after ingestion of multiple pills at home.  On exam, she is hypotensive, tachycardic, confused, and has dilated pupils with dry skin.  The patient has most likely ingested amitriptyline tablets given the history provided in the question.  Amitriptyline is a tricyclic antidepressant medication.  Despite the clear history, it is very important to check levels for possible other coingestants, like paracetamol (APAP) and salicylates.

Tricyclic antidepressants (TCAs) impact many different receptors in the body, so the clinical presentation of a patient with TCA overdose can vary considerably.  Important features to remember are cardiovascular toxicity with a widened QRS and hypotension, as well as an anticholinergic toxidrome.  A 12-lead EKG should be ordered early in any case of possible overdose, and an EKG in TCA overdose is a crucial step in evaluation.  Supportive care and IV sodium bicarbonate are the mainstays of treatment for TCA overdose.  See the table below for details regarding the clinical features and treatment of these patients. 

IV Physostigmine (Choice A) can be used to treat an anticholinergic toxidrome along with supportive care and benzodiazepines.  This patient does appear to have an anticholinergic toxidrome, but there is a high suspicion for TCA overdose.  Physostigmine should be avoided in TCA overdose due to data indicating worse outcomes in TCA overdose patients who receive physostigmine.  IV Norepinephrine (Choice B) may eventually be required to manage this patient’s hypotension.  However, IV fluids and sodium bicarbonate to reverse the cardiac toxicity should be used first.  IV Metoprolol (Choice D) may help relieve the tachycardia, but it would worsen the patient’s hypotension and shock state.   The best next step is IV Sodium bicarbonate (Choice C), which is the treatment for TCA overdose.  Sodium bicarbonate prevents TCA binding to cardiac sodium channels, thereby stabilizing the heart and preventing cardiac dysrhythmias and death. Sodium bicarbonate is given as an infusion until the QRS interval shortens <100msec and the hypotension improves.