Chemical Structure/Formula:
C17H19N3O

Mechanism of Action:
Phentolamine is a non-selective alpha-adrenergic antagonist. It blocks alpha-1 and alpha-2 receptors, which leads to vasodilation and a decrease in blood pressure.
Uses:
It is used to treat high blood pressure caused by pheochromocytoma (a type of adrenal gland tumor). It is also used to prevent tissue necrosis following the extravasation of noradrenaline.
Side Effects:
Common side effects include hypotension, tachycardia, flushing, and headache. It may also cause gastrointestinal upset and nasal congestion.