What is a primary characteristic of dihydropyridine calcium channel blockers (CCBs)?

A primary characteristic of dihydropyridine calcium channel blockers (CCBs) is systemic vasodilation. These medications primarily target vascular smooth muscle, leading to the relaxation of these muscles and subsequent dilation of blood vessels. This mechanism results in decreased peripheral resistance, which can help reduce blood pressure in patients with hypertension.

Dihydropyridine CCBs, such as amlodipine and nifedipine, do not significantly affect the heart's ability to contract or its rate of firing, which is why options related to myocardial vasodilation, reduction in heart rate, and increased contractility are not accurate primary characteristics. Their principal action is aimed at the vasculature rather than direct cardiac effects, differentiating them from non-dihydropyridine CCBs, which can affect the heart rate and contractility. Thus, the systemic vasodilation effect is the defining feature of dihydropyridine calcium channel blockers.