Phentolamine Mesylate Lyophilized Injection

Category: Alpha-adrenergic blocker (Non-selective)
Form: Lyophilized (freeze-dried) powder for reconstitution and intravenous (IV) or intramuscular (IM) administration

Uses:

• Management of hypertensive emergencies, especially those caused by pheochromocytoma.

• Prevention and treatment of tissue necrosis or extravasation caused by alpha-agonist drugs (e.g., norepinephrine or dopamine).

• Occasionally used in diagnostic testing for pheochromocytoma.

Mechanism of Action:

• Phentolamine is a non-selective alpha-adrenergic antagonist.

• Blocks alpha-1 and alpha-2 receptors, causing vasodilation and reduced peripheral vascular resistance.

• Leads to lowered blood pressure and improved tissue perfusion.

• In cases of extravasation, it reverses local vasoconstriction, reducing tissue damage.

Administration:

• Lyophilized powder is reconstituted with a suitable diluent before injection.

• Administered intravenously or intramuscularly, depending on the indication.

• Dosage is titrated carefully based on blood pressure response or site of extravasation.

Side Effects:

• Cardiovascular: hypotension, reflex tachycardia, arrhythmias.

• Gastrointestinal: nausea, vomiting.

• Other: dizziness, headache, flushing.

• Local reactions at injection site may occur.

Precautions:

• Continuous blood pressure and heart rate monitoring is essential during IV administration.

• Use cautiously in patients with coronary artery disease or severe heart failure.

• Avoid rapid IV injection to prevent severe hypotension.

• Monitor injection site carefully when used for extravasation management.

Summary:
Phentolamine Mesylate Lyophilized Injection is a non-selective alpha-blocker used for hypertensive crises, pheochromocytoma management, and reversal of alpha-agonist extravasation. It works by blocking alpha receptors, causing vasodilation and improved blood flow. Administered intravenously or intramuscularly after reconstitution, it requires careful monitoring due to risks of hypotension and reflex tachycardia.