Clonidine: Encyclopedia II - Clonidine - Mechanism of action

Clonidine - Mechanism of action

Clonidine is a centrally-acting alpha-2 agonist. It selectively stimulates receptors in the brain that monitor catecholamine levels in the blood. These receptors close a feedback loop that begins with descending sympathetic nerves from the brain that control the production of catecholamines (epinephrine, also known as adrenaline, and norepinephrine) in the adrenal medulla. By fooling the brain into believing that catecholamine levels are higher than they really are, clonidine causes the brain to reduce its signals to the adrenal medulla, which in turn lowers catecholamine production and blood levels. The result is a lowered heart rate and blood pressure, with side effects of dry mouth and fatigue.

An analogy would be the lowering the temperature of a house by holding a lit match under the thermostat connected to the furnace.

Adapted from the Wikipedia article "Mechanism of action", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki