50-year-old woman presents to the emergency department after taking an overdose of propranolol. Which of the following describes the mechanism of action with this agent?
A Decreased membrane-stabilizing activity
B Increased production of cyclic adenosine monophosphate
C Inhibition of alpha-adrenoceptors
D Inhibition of beta-adrenoceptors
Answer: D. Beta adrenergic antagonists, more commonly referred to as beta-blockers, inhibit beta-adrenoceptors. They are used in the treatment of a number of disorders including hypertension, heart failure, arrhythmias, ischemic heart disease, migraine headaches, tremor, aortic dissection and portal hypertension. Beta-blockers competitively inhibit epinephrine and norepinephrine, which results in the blunting of multiple metabolic and cardiovascular effects normally regulated by these circulating catecholamines.
The MC seen clinical manifestations of beta-blocker overdose include hypotension and bradycardia.