What is a common adverse effect of non-dihydropyridine calcium channel blockers?

• A. Hypertension and tachycardia.
• B. Hyperkalemia.
• C. Hyperglycemia.
• D. Cardiac conduction abnormalities and peripheral edema; reduced heart rate and contractility.

Answer: (D)

Non-dihydropyridine calcium channel blockers primarily affect the heart by blocking L-type calcium channels in cardiac muscle and the AV node. This reduces calcium entry during depolarization, leading to a slower heart rate (negative chronotropy) and weaker contractions (negative inotropy), and it slows conduction through the AV node (negative dromotropy). Because of these effects, they can cause cardiac conduction abnormalities such as AV block and bradycardia. They also produce some peripheral vasodilation, which can raise capillary pressure and contribute to peripheral edema. Taken together, these drugs commonly produce conduction abnormalities and peripheral edema along with reduced heart rate and contractility, which is why this option fits best. The other options describe effects not typically associated with these medications, such as reflex tachycardia or metabolic disturbances.