Brands, Medical Use, Clinical Data
Drug Category
- Antihypertensive Agents
- Sympatholytics
Dosage Forms
Brands / Synonyms
Oraverse; Phenotolamine; Phentalamine; Phentolamine; Phentolamine Mesilate; Phentolamine Mesylate; Phentolamine Mesylate [USAN]; Phentolamine Methanesulfonate; Phentolamine Methanesulphonate; Phentolamine, Methyl Sulfonate; Regitin; Regitin Methanesulphonate; Regitine; Regitine Mesylate; Regitine Methanesulfonate; Regitipe; Rogitine
Indications
For the prevention or treatment of dermal necrosis and sloughing following intravenous administration or extravasation of norepinephrine. Also for the prevention or control of hypertensive episodes that may occur in a patient with pheochromocytoma as a result of stress or manipulation during preoperative preparation and surgical excision.
Pharmacology
Phentolamine is indicated for the control of episodes of hypertension and sweating that occur with a disease called pheochromocytoma. If tachycardia is excessive, it may be necessary to use a beta-blocking agent concomitantly. Phentolamine is a long-acting, adrenergic, alpha-receptor blocking agent which can produce and maintain "chemical sympathectomy" by oral administration. It increases blood flow to the skin, mucosa and abdominal viscera, and lowers both supine and erect blood pressures. It has no effect on the parasympathetic system. Phentolamine works by blocking alpha receptors in certain parts of the body. Alpha receptors are present in the muscle that lines the walls of blood vessels. When the receptors are blocked by Phentolamine, the muscle relaxes and the blood vessels widen. This widening of the blood vessels results in a lowering of blood pressure.
Mechanism of Action
Phentolamine produces its therapeutic actions by blocking alpha receptors, leading to a muscle relaxation and a widening of the blood vessels. This widening of the blood vessels results in a lowering of blood pressure.
Absorption
Not Available
Toxicity
Not Available
Biotrnasformation / Drug Metabolism
Not Available
Contraindications
Myocardial infarction, history of myocardial infarction, coronary insufficiency, angina, or other evidence
suggestive of coronary artery disease; hypersensitivity to phentolamine or related compounds.
Drug Interactions
Diagnosis of pheochromocytoma - phentolamine blocking test.
The test is most reliable in detecting pheochromocytoma in patients with sustained hypertension and least reliable in those with paroxysmal hypertension. False-positive tests may occur in patients with hypertension without pheochromocytoma.
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