Dihydropyridines are a class of chemical compounds that contain a six-membered ring with five carbon atoms and one nitrogen atom. They are primarily used in medicine as calcium channel blockers, which help to relax blood vessels and lower blood pressure. Common examples include amlodipine and nifedipine. These compounds work by inhibiting the influx of calcium ions into smooth muscle cells, leading to vasodilation. This mechanism makes dihydropyridines effective in treating conditions like hypertension and angina. They are generally well-tolerated, but may have side effects such as swelling or flushing.