Guanethidine is an adrenergic neural blocker that has been used for treating hypertension.
Guanethidine is a polar guanidine compound which is taken up into the adrenergic nerve endings by active amine transport, and has three important facets of action:
(a) It displaces NA (noradrenaline) from storage granules stoichiometrically.
(b) Inhibits nerve impulse coupled release of NA (noradrenaline).
(c) Engages and blocks NA (noradrenaline) uptake mechanism at the axonal membrane.
It was used in the past because of its above mentioned effects in decreasing noradrenaline that could lower the blood pressure. Guanethidine has gone out of use now due to marked side effects.