What is a unique side effect of the calcium channel blocker amlodipine?

The unique side effect of the calcium channel blocker amlodipine is peripheral edema. This phenomenon occurs because amlodipine causes dilation of peripheral blood vessels, leading to an increase in hydrostatic pressure in the capillaries of the lower extremities. As the capillary pressure rises, it can result in fluid accumulation in the tissues, manifesting as swelling, particularly in the ankles and feet.

While other side effects can occur with different antihypertensive agents, peripheral edema is particularly associated with amlodipine and other dihydropyridine calcium channel blockers. The occurrence of this side effect may be related to the medication's action on the vascular smooth muscle, leading to vasodilation and subsequent fluid retention.

Bradycardia is more commonly associated with non-dihydropyridine calcium channel blockers. A dry cough is notably linked to ACE inhibitors due to their mechanism of increasing bradykinin levels, while hypokalemia is often associated with diuretics, rather than calcium channel blockers. Thus, peripheral edema stands out as a unique and notable side effect of amlodipine.