- Phentolamine is a non-selective alpha-adrenergic antagonist (alpha-blocker) used primarily to manage and treat hypertensive emergencies, particularly those caused by pheochromocytoma.
- Phentolamine works by blocking alpha-1 and alpha-2 adrenergic receptors, leading to vasodilation, reduced blood pressure, and improved blood flow.
Chemical Structure & Formula:
- Contains an imidazoline fragment linked to a substituted aromatic moiety (often an indanyl derivative) with a urea or carbamoyl linkage.
- Approximate Formula: C₁₇H₂₇N₅O₂
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Mechanism of Action:
- Acts as a competitive, nonselective antagonist at both α₁ and α₂ receptors.
- Blocks the actions of norepinephrine and epinephrine on vascular smooth muscle, leading to vasodilation and blood pressure reduction.
- Its rapid onset makes it useful in acute settings.
Side Effects of Phentolamine:
- Marked hypotension
- Reflex tachycardia
- Headache
- Potential arrhythmias due to abrupt vasodilation
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Clinical Uses of Phentolamine:
- Employed in hypertensive emergencies, particularly in pheochromocytoma, and used in certain diagnostic procedures related to erectile dysfunction
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