Guanethidine

Mechanism of action:

Its neurotransmission is almost similar to the process of norepinephrine.

It replaces norepinephrine in the transmitter vesicles resulting in the reduction of norepinephrine in the nerve endings. This causes the inhibition of the release of norepinephrine from the sympathetic nerve endings.

Actions:
As it causes the replacement of norepinephrine, so firstly, mild cardiac stimulation and minor form of hypertension that lasts for short duration, occurs.

This is followed by bradycardia and hypotension (orthostatic type of hypotension occurs mostly as it decreases vasoconstrictor reflexes.)

It promotes tissues sensitivity to catecholamines.

Therapeutic uses::
In combination with diuretic and vasodilator it can be used for moderate to severe type of hypertension.

Adverse effects:
Weakness, Orthostatic hypotension, Diarrhea

Contraindications:
It is contraindicated in patients of
1. Pheochromocytoma
2. Serious coronary artery disease
3. Cerebrovascular insufficiency
4. While using MAO inhibitors