Toxicology

β-Blocker overdoses are characterized by hypotension, bradycardia, and prolonged atrioventricular

conduction.

hypotension, prolonged atrioventricular conduction, bradycardia, lethargy, hyperglycemia, and

depressed consciousness. The dihydropyridine agents act peripherally and are primarily associated with

vasodilation, hypotension, and reflex tachycardia. However, this receptor selectivity is lost at high doses

Consider gastric lavage or activated charcoal if patients present within 1–2 hours of overdose. Whole

bowel irrigation is recommended for delayed presentation or for sustained- or extended-release

formulations.

Goal of therapy is a mean arterial pressure greater than 65 mm Hg or systolic blood pressure (SBP)

greater than 90 mm Hg.

Administer isotonic fluids (0.9% sodium chloride or lactated Ringer solution) at 20–30 mL/kg

(preferred) or colloidal solutions (e.g., albumin 5% 250 mL).

Administer intravenous calcium chloride or calcium gluconate (first line therapy for calcium channel

blocker toxicity).

Calcium chloride 1–2 g (central line is preferred; however, bolus doses may be administered in a

peripheral line if needed)

Calcium gluconate 3–6 g. Repeat dose may be given every 15–30 minutes; may also consider

continuous infusion at 0.3–0.7 mEq/kg/hour.

Consider sodium bicarbonate for QRS widening, severe acidosis, or dysrhythmia: 1– 2 mEq/kg bolus;

may consider a continuous infusion if symptoms persist.

Treat symptomatic bradycardia and hypotension as follows:

Atropine 0.5–1 mg intravenously; if no response, continue to the following options:

Glucagon 5–10 mg (100 mcg/kg) intravenous push for 1 minute (consider for β-blocker toxicity

only). If symptom response is achieved from the bolus, may consider a continuous intravenous

infusion initiated at the same rate (milligrams per hour) as the bolus dose that achieved response.

Stimulates adenylate cyclase, which increases intracellular cAMP (cyclic adenosine

monophosphate), leading to increased inotropy, chronotropy, and cardiac conduction

ii.

Adverse effects include nausea, vomiting, and hyperglycemia. Consider premedicating with

an antiemetic intravenously before bolus dosing of glucagon to decrease the risk of nausea and

vomiting.

iii.

Use with caution with decreased mental status because of possible aspiration or airway

obstruction (also causes lower esophageal sphincter relaxation).

iv.

Not recommended as a preferred treatment option for calcium channel blockers because of

limited efficacy and cost

Norepinephrine continuous infusion initiated at 2–5 mcg/minute (0.1 mcg/kg/minute) and titrated

to target blood pressure in the setting of vasodilatory shock

Epinephrine continuous infusion should be initiated at 1 mcg/minute (0.01–0.1 mcg/kg/minute) and

titrated to target hemodynamic parameters. Dobutamine continuous infusion should be initiated at

2–20 mcg/kg/min and titrated to target hemodynamic parameters. Dopamine is not recommended

in this setting.

Transcutaneous or transvenous pacing or intra-aortic balloon pumps may be required in refractory

cases