Ganglionic Blockers: Agents having as their major action the interruption of neural transmission at nicotinic receptors on postganglionic autonomic neurons. Because their actions are so broad, including blocking of sympathetic and parasympathetic systems, their therapeutic use has been largely supplanted by more specific drugs. They may still be used in the control of blood pressure in patients with acute dissecting aortic aneurysm and for the induction of hypotension in surgery.Hexamethonium: A nicotinic cholinergic antagonist often referred to as the prototypical ganglionic blocker. It is poorly absorbed from the gastrointestinal tract and does not cross the blood-brain barrier. It has been used for a variety of therapeutic purposes including hypertension but, like the other ganglionic blockers, it has been replaced by more specific drugs for most purposes, although it is widely used a research tool.Trimethaphan: A nicotinic antagonist that has been used as a ganglionic blocker in hypertension, as an adjunct to anesthesia, and to induce hypotension during surgery.Chlorisondamine: A nicotinic antagonist used primarily as a ganglionic blocker in animal research. It has been used as an antihypertensive agent but has been supplanted by more specific drugs in most clinical applications.Calcium Channel Blockers: A class of drugs that act by selective inhibition of calcium influx through cellular membranes.