Calcium channel blocking drugs (CCBs) bind to different calcium channel sites and have varying effects on cardiac and vascular tissue. Nifedipine is the most selective vasodilator while verapamil and diltiazem are more equipotent between cardiac tissue and vasculature. CCBs reduce afterload through peripheral vasodilation but have little effect on preload or contractility. Nifedipine is most likely to cause hypotension and reflex tachycardia due to its strong vasodilatory effects, while verapamil may worsen heart failure or cause heart block.