29-05-2025
Rapid Rx Quiz: Calcium-Channel Blockers
Calcium-channel blockers (CCBs) play a central role in the treatment of hypertension, angina, and certain cardiac arrhythmias and are among the most commonly prescribed drugs in the United States. Beyond their US Food and Drug Administration–approved uses, CCBs have found a place in treating several off-label conditions. With their widespread use, however, comes the responsibility of understanding their pharmacodynamics, drug-drug interactions, and potential toxicities.
How much do you know about CCBs? Test yourself with this short quiz.
Off-label uses for CCBs include Raynaud phenomenon, migraines, and subarachnoid hemorrhage. CCBs do not treat depression; in fact, their use has been associated with depression. Verapamil might reduce diastolic dysfunction, but this is not a mainstream use. The most common CCBs are relatively weight neutral.
Learn more about Raynaud phenomenon.
Including lightheadedness, specific adverse and serious adverse events from CCB use are bradycardia, constipation, headaches, flushing, worsening cardiac output, and peripheral edema, possibly from fluid redistributing from the intravascular space.
Learn more about dizziness and vertigo.
A recent study found that amlodipine was involved in the majority of overdose cases, accounting for 62% of all CCB overdoses. This far surpasses other agents such as lercanidipine (12%), diltiazem (11%), verapamil (10%), and felodipine (5%). The lower incidence of overdoses involving lercanidipine, diltiazem, verapamil, and felodipine corresponds with their declining presence in current hypertension treatment guidelines.
Although amlodipine is involved in more overdose cases overall, the study underscores that the severity of overdose varies significantly by CCB class. Nondihydropyridines, such as diltiazem and verapamil, were associated with markedly higher rates of life-threatening complications, including dysrhythmias (33-35% of cases) and intensive care unit (ICU) admissions (52% and 30%, respectively). In contrast, amlodipine showed much lower rates of dysrhythmias (1%) and ICU admissions (18%).
Learn more about CCB toxicity.
Many of the signs and symptoms of CCB toxicity are similar to normal CCB adverse events, making diagnosis challenging. A blood test can aid in diagnosis; abnormal findings that suggest CCB toxicity include acidosis, hyperglycemia, and hypokalemia. Neutrophilia has no established connection.
Learn more about CCB toxicity.
Combining diltiazem or verapamil with direct oral anticoagulants might increase risk for bleeding or clotting complications, though previous research has shown mixed results.
A recent study found no evidence of increased risk when direct oral anticoagulants were used alongside diltiazem or verapamil. However, patients who began direct oral anticoagulant therapy while already taking diltiazem had higher rates of overall mortality and cardiovascular-related death within 30 days, compared with those taking anticoagulants alone.
Learn more about diltiazem.
