Pharmacology - Phenoxybenzamine

Pharmacology - Phenoxybenzamine 
​The action of phenoxybenzamine 
Vasodilation and postural hypotension are two outcomes that are avoided when alpha1-receptors are blocked.
The effects of blocking alpha 2 receptors include a decrease in the action of NA on the 2 receptors on the varicosity and an increase in the release of NA from the varicosity, both of which can lead to atrial fibrillation and an increase in cardiac output.

Mode of Action 
Phentolamine prevents the function of NA by binding to alpha receptors in a covalent manner, which is known as an irreversible binding. However, the action of phentolamine can be reversed.

The process of absorbing, distributing, and eliminating 
3 hours is the plasma half-life, which is longer in older people. When administered orally, the plasma half-life is approximately 12 hours, and the duration of effect is up to several days due to the irreversible binding to the receptor.

Use in clinical settings 
Phaeochromocytoma sufferers can benefit from this treatment.

Adverse Effects
The presence of tachycardia and postural hypotension.