What are the two main classes of calcium channel blockers (CCBs)?

The correct answer identifies the two main classes of calcium channel blockers (CCBs) as non-dihydropyridines (Non-DHPs) and dihydropyridines (DHPs). These classifications are based on their chemical structure and mechanism of action.

Non-DHPs include medications such as verapamil and diltiazem. They are primarily used to decrease heart rate and contractility, making them suitable for managing conditions like hypertension, angina, and certain arrhythmias. Their effect on the heart is more pronounced, which is why they also have a greater impact on reducing heart rate.

On the other hand, DHPs, such as amlodipine and nifedipine, primarily target vascular smooth muscle. They are known for their ability to induce vasodilation, which helps significantly lower blood pressure. This class is widely used in the treatment of hypertension and angina but has fewer effects on heart rate compared to non-DHPs.

The other answer choices do not accurately classify calcium channel blockers. The distinction as “selective” and “non-selective” does not apply to CCBs specifically. Although CCBs can vary in duration of action (long-acting vs. short