Phenotolamine;Phentalamine;Phentolamine Mesilate;Phentolamine Mesylate;Phentolamine Mesylate [USAN];Phentolamine Methanesulfonate;Phentolamine Methanesulphonate;Phentolamine, Methyl Sulfonate;Regitin;Regitin Methanesulphonate;Regitine;Regitine Mesylate;Regitine Methanesulfonate;Regitipe;Rogitine;

A nonselective alpha-adrenergic antagonist. It is used in the treatment of hypertension and hypertensive emergencies, pheochromocytoma, vasospasm of raynaud disease and frostbite, clonidine withdrawal syndrome, impotence, and peripheral vascular disease. [PubChem]

• Bedford laboratories div ben venue laboratories inc
• Glaxosmithkline
• Mcneil consumer healthcare
• Novalar pharmaceuticals inc
• Novartis pharmaceuticals corp
• Perrigo co
• Ranbaxy laboratories ltd
• Sanofi aventis us llc

• Bedford Labs
• Ben Venue Laboratories Inc.
• Novalar Pharmaceuticals Inc.
• Novartis AG
• Novocol Pharmaceutical Canada

Synthesis Reference	Not Available
General Reference	Not Available

Type	small molecule

Classes

Phenols and Derivatives Aminophenols and Derivatives

Substructures

Hydroxy Compounds Imidazolines Carboxylic Acids and Derivatives Phenols and Derivatives Aliphatic and Aryl Amines Benzene and Derivatives Aminophenols and Derivatives Imidazoles Heterocyclic compounds Aromatic compounds Carboxamidines Imines Phenyl Esters Anilines

ANTIHYPERTENSIVES 降血压;

Indication	Used as an aid for the diagnosis of pheochromocytoma, and may be administered immediately prior to or during pheochromocytomectomy to prevent or control paroxysmal hypertension resulting from anesthesia, stress, or operative manipulation of the tumor. Phentolamine has also been used to treat hypertensive crisis caused by sympathomimetic amines or catecholamine excess by certain foods or drugs in patients taking MAO inhibitors, or by clonidine withdrawal syndrome. Other indications include the prevention of dermal necrosis and sloughing following IV administration or extravasation of norepinephrine, decrease in impedance to left ventricular ejection and the infarct size in patients with MI associated with left ventricular failure, treatment of erectile dysfunction through self-injection of small doses combined with papaverine hydrochloride into the corpus cavernosum, and as an adjunct to the management of cocaine overdose to reverse coronary vasoconstriction following use of oxygen, benzodiazepines,and nitroglycerin.
Pharmacodynamics	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 competitively blocking alpha-adrenergic receptors (primarily excitatory responses of smooth muscle and exocrine glands), 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. The action of phentolamine on the alpha adrenergic receptors is relatively transient and the blocking effect is incomplete. The drug is more effective in antagonizing responses to circulating epinephrine and/or norepinephrine than in antagonizing responses to mediator released at the adrenergic nerve ending. Phentolamine also stimulates β-adrenergic receptors and produces a positive inotropic and chronotropic effect on the heart and increases cardiac output.
Absorption	Not Available
Volume of distribution	Not Available
Protein binding	Not Available
Metabolism	Not Available
Route of elimination	10-13% of the drug is excreted unchanged in urine, and the fate of the remainder of the drug is unknown.
Half life	19 minutes
Clearance	Not Available
Toxicity	Not Available
Affected organisms	Humans and other mammals
Pathways	Not Available

Properties
State	solid
Experimental Properties	Property Value Source melting point 174.5 °C PhysProp logP 3.3 Not Available
Predicted Properties	Property Value Source water solubility 2.72e-01 g/l ALOGPS logP 2.91 ALOGPS logP 2.52 ChemAxon logS -3 ALOGPS pKa (strongest acidic) 9.78 ChemAxon pKa (strongest basic) 9.02 ChemAxon physiological charge 1 ChemAxon hydrogen acceptor count 4 ChemAxon hydrogen donor count 2 ChemAxon polar surface area 47.86 ChemAxon rotatable bond count 4 ChemAxon refractivity 84.25 ChemAxon polarizability 31.37 ChemAxon

Drug	Interaction
Tadalafil	Tadalafil may enhance the hypotensive effect of Phentolamine. Monitor for hypotension during concomitant therapy.
Tamsulosin	Concomitant use of alpha1-adrenergic antagonists, Tamsulosin and Phentolamine, may result in additive antihypertensive effects. Combination therapy is not recommended.
Treprostinil	Additive hypotensive effect. Monitor antihypertensive therapy during concomitant use.
Vardenafil	Additive hypotensive effects of the PDE5 inhibitor, Vardenafil, and alpha1-blocker, Phentolamine, may occur. Monitor for hypotension during concomitant therapy.

Not Available