Prozasin

Pharmacology 10,161 Views

Selective alpha 1 blocker, causing decrease in TPR and venous return. It has no effects on alpha 2 receptors.

Pharmacokinetics

It has a half life of 3 hours. Its bioavailability is 50%.

Adverse Effects

Adverse effects include:

Postural hypotension

Causes first dose response

When administered, causes postural hypotension and the person may collapse. To cope this, first a small dose is administered, which is increased very slowly. It is preferably administered at night, and the patient is advised to stay in bed in lying position. Sudden withdrawal is avoided and other hypertensives are withdrawn. Otherwise severe hypertension might occur. The patient is strictly warned about the side effects.

Phenoxybenzamine	Prazosin
Irreversible antagonism	Reversible antagonism
Alpha 1 and 2 selective	Alpha 1 selective blockers
Decrease TPR and B.P, produce vasodilatation and reflex tachycardia	Veins are less affected, less reflex tachycardia and less decrease in TPR and B.P
May cause sedation, nausea and fatigue	May cause 1^st dose phenomenon
Used in pheochromocytoma	Used in HTN and BPH
Can cross blood brain barrier (Antihistamine in nature)	Cannot cross blood brain barrier