Phenbenzamine

Phentolamine is a reversible non-selective alpha-adrenergic antagonist. Its primary action is competitive inhibition of alpha-1 adrenergic receptors, but it also has alpha-2 adrenergic receptor blocking activity.

Etymology

The term "Phentolamine" is derived from the chemical structure of the drug, which consists of a phenyl ring and an imidazoline ring. The "phen-" prefix refers to the phenyl ring, while "-tolamine" refers to the imidazoline ring.

Pharmacology

Phentolamine is used to treat hypertension and pheochromocytoma, a rare tumor of the adrenal gland which secretes catecholamines, usually norepinephrine and epinephrine. It is also used to prevent dermal necrosis and sloughing following intravenous administration or extravasation of norepinephrine.

Mechanism of Action

Phentolamine works by blocking alpha-1 and alpha-2 adrenergic receptors, which are found on the smooth muscle of blood vessels. This causes the blood vessels to relax and dilate, which lowers blood pressure.

Side Effects

Common side effects of phentolamine include tachycardia, arrhythmia, and hypotension. Less common side effects include nausea, vomiting, and diarrhea.

Related Terms

• Alpha-1 adrenergic receptor
• Alpha-2 adrenergic receptor
• Hypertension
• Pheochromocytoma
• Adrenal gland
• Catecholamines
• Norepinephrine
• Epinephrine
• Dermal necrosis
• Sloughing
• Smooth muscle
• Tachycardia
• Arrhythmia
• Hypotension
• Nausea
• Vomiting
• Diarrhea

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