How does guanfacine function as an antihypertensive?

Guanfacine functions as an antihypertensive primarily by stimulating alpha-2 adrenergic receptors in the central nervous system. This action leads to a reduction in sympathetic outflow from the brain to the periphery, resulting in decreased norepinephrine release and reduced arterial tone. Consequently, this results in vasodilation and lower blood pressure. The central mechanism of action is integral to its effectiveness as it reduces the overall workload on the heart and decreases peripheral resistance.

Other mechanisms of action are not associated with guanfacine. For instance, inhibiting calcium channels would typically lead to relaxation of smooth muscle and vasodilation but is not how guanfacine works. Similarly, stimulating alpha-1 adrenergic receptors usually causes vasoconstriction, which contradicts the desired effect for an antihypertensive. Blocking sodium channels does not play a role in the mechanism of guanfacine and is more characteristic of certain antiarrhythmic drugs. Understanding guanfacine's unique action at alpha-2 receptors is crucial for comprehending how various antihypertensive medications can produce their effects through different pathways.