New York, NY: McGraw-Hill Education 2015. In: Hoffman RS, Howland MA, Lewin NA, Nelson LS, Goldfrank LR, eds. In addition, propranolol (Inderal) is not cardioselective and blocks both beta-1 and beta-2 receptors.Brubacher JR. Answer E is incorrect because cardioselective beta blockers target Beta-1 receptors found in cardiac muscle whereas Beta-2 receptors are primarily located in the lungs. Metoprolol succinate (Toprol XL) and metoprolol tartrate (Lopressor) are both metabolized via CYP 2D6, making answer D correct as poor metabolizers may allow accumulation leading to toxicity. It is important to counsel patients with diabetes who take beta blockers that these symptoms of hypoglycemia may be masked, but sweating is not masked by beta blockers.

Answer C is correct because beta blockers can mask tachycardia during a hypoglycemic episode. If used for HFrEF, the only three beta blockers recommended are metoprolol succinate (Toprol XL), bisoprolol (Ziac) and carvediol (Coreg). Beta blockers are considered a part of first-line treatment for patients with ischemic heart disease, such as our patient who has had a previous myocardial infarction, and in patients with heart failure with reduced ejection fraction (HFrEF).

Answer B is incorrect because beta blockers are not first line treatment for uncomplicated hypertension due to worse outcomes compared to other first-line agents (increased risk of stroke).

It is important to also note that during beta blocker toxicity, many other drugs are also used as part of treatment such as fluids to manage hypotension and even sometimes glucagon (Gvoke) which is considered an antidote for beta blocker toxicity. What instead would potentially be used is atropine (AtroPen), an anticholinergic agent that increases cardiac output and treats bradycardia. Answer A is incorrect because adenosine (Adenocard/Adenoscan) is a Class IV antiarrhythmic used for paroxysmal supraventricular tachycardia (PSVT) and would lower the patient's heart rate even further.

Beta blocker overdose antidote