Pheochromocytoma Medication

Updated: Oct 10, 2017
  • Author: Michael A Blake, MBBCh, MRCPI, FRCR; Chief Editor: George T Griffing, MD  more...
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Medication

Medication Summary

Medical therapy is used for preoperative preparation prior to surgical resection, [63] for acute hypertensive crises, and as primary therapy for patients with metastatic pheochromocytomas. Preoperative preparation requires combined alpha and beta blockade to control blood pressure and to prevent an intraoperative hypertensive crisis. Alpha-adrenergic blockade, in particular, is required to control blood pressure and prevent a hypertensive crisis. High circulating catecholamine levels stimulate alpha receptors on blood vessels and cause vasoconstriction.

Beta blockers are used if significant tachycardia occurs after alpha blockade. Beta blockers are not administered until adequate alpha blockade has been established, however, because unopposed alpha-adrenergic receptor stimulation can precipitate a hypertensive crisis. Noncardioselective beta blockers, such as propranolol (Inderal) or nadolol (Corgard), are the usual choice; however, cardioselective agents, such as atenolol (Tenormin) and metoprolol (Lopressor), also may be used.

Labetalol (Trandate, Normodyne) is a noncardioselective beta-adrenergic blocker and selective alpha-adrenergic blocker that has been shown to be effective in controlling hypertension associated with pheochromocytoma. However, it has also been associated with paradoxic episodes of hypertension thought to be secondary to incomplete alpha blockade. Thus, its use in the preoperative treatment of patients with pheochromocytoma is controversial.

During surgery, intravenous phentolamine, a rapid-acting alpha-adrenergic antagonist, is used to control blood pressure. Rapid-acting intravenous beta blockers, such as esmolol, are also used to normalize blood pressure.

Selective alpha1 blocking agents, such as prazosin (Minipress), terazosin (Hytrin), and doxazosin (Cardura), have more favorable adverse effect profiles and are used when long-term therapy is required (metastatic pheochromocytoma). These medications are not used to prepare patients for surgery, because of their incomplete alpha blockade.

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Alpha Blockers, Antihypertensives

Phenoxybenzamine hydrochloride (Dibenzyline)

This is a long-acting adrenergic alpha-receptor blocker that can produce and maintain a chemical sympathectomy. Phenoxybenzamine lowers supine and upright blood pressure. It does not affect the parasympathetic nervous system. Reflex tachycardia is a concern and may require the addition of a beta blocker.

Phentolamine mesylate (OraVerse)

Phentolamine mesylate is a nonselective alpha-adrenergic blocking agent that produces transient and incomplete alpha-adrenergic blockade. This agent is often used immediately before or during adrenalectomy to prevent or control paroxysmal hypertension resulting from anesthesia, stress, or operative manipulation of the tumor. It is an alpha1- and alpha2-adrenergic blocking agent that blocks circulating epinephrine and norepinephrine action, reducing hypertension that results from catecholamine effects on alpha receptors.

Prazosin (Minipress, Prazin, Prazo)

Prazosin is a quinazoline compound that is a selective alpha1 adrenergic antagonist. Prazosin causes peripheral vasodilation by selective, competitive inhibition of vascular postsynaptic alpha1-adrenergic receptors, thus reducing peripheral vascular resistance and blood pressure.

Terazosin (Hytrin)

Terazosin is a quinazoline compound that is a a selective alpha1 adrenergic antagonist. Terazosin causes peripheral vasodilation by selective, competitive inhibition of vascular postsynaptic alpha1-adrenergic receptors, thus reducing peripheral vascular resistance and blood pressure.

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BPH, Alpha Blocker

Doxazosin mesylate (Cardura, Cardura XL)

Doxazosin mesylate is a quinazoline compound that is a selective alpha1-adrenergic antagonist. It inhibits postsynaptic alpha-adrenergic receptors, resulting in the vasodilation of veins and arterioles and a decrease in total peripheral resistance and blood pressure.

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Vasodilators

Nitroprusside sodium (Nipride, Nitropress, Sodium Nitroprusside)

Nitroprusside is a direct vasodilator that relaxes arterial vessels and venous smooth muscle. It has a short half-life and its effect disappears within 5 minutes of stopping infusion. The drug may be used to control paroxysmal hypertension intraoperatively. Nitroprusside produces vasodilation and increases the inotropic activity of the heart. At higher dosages, it may exacerbate myocardial ischemia by increasing the heart rate.

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Beta Blockers, Nonselective

Propranolol (Inderal LA, InnoPran XL)

Propranolol is a nonselective beta-adrenergic receptor blocker. The drug has membrane-stabilizing activity and decreases the automaticity of contractions.

After primary treatment with an alpha receptor blocker, propranolol may be used as adjunctive therapy if control of tachycardia becomes necessary before or during surgery. It may be used to treat excessive beta receptor stimulation in patients with inoperable metastatic pheochromocytoma. Propranolol is not suitable for the emergency treatment of hypertension; do not administer it intravenously in hypertensive emergencies.

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Beta Blockers, Beta1 Selective

Atenolol (Tenormin)

Atenolol selectively blocks beta1 (cardioselective) receptors, with little or no effect on beta2 types. After primary treatment with an alpha receptor blocker, atenolol may be used as adjunctive therapy if control of tachycardia becomes necessary before or during surgery.

Metoprolol (Lopressor)

Metoprolol selectively blocks beta1 (cardioselective) receptors, with little or no effect on beta2 types at low doses. However, at higher plasma concentrations, metoprolol also inhibits beta2 receptors. After primary treatment with an alpha receptor blocker, metoprolol may be used as adjunctive therapy if control of tachycardia becomes necessary before or during surgery.

Esmolol (Brevibloc)

Esmolol is a short-acting beta1 selective beta blocker administered via continuous intravenous infusion. In low doses, esmolol selectively blocks sympathetic stimulation mediated by beta1-adrenergic receptors in the heart and vascular smooth muscle. Esmolol's extremely short duration of action makes the drug useful for acute control of hypertension or certain supraventricular arrhythmias.

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Antihypertensives, Other

Metyrosine (Demser)

Metyrosine inhibits tyrosine hydroxylase, the rate-limiting step in catecholamine synthesis. In patients with pheochromocytoma, administration of metyrosine reduces catecholamine biosynthesis by 35-80%, as measured by urinary catecholamine levels.

Metyrosine is indicated in patients with pheochomocytoma who are awaiting surgery, for long-term management of patients with malignant pheochromocytoma, or in cases of pheochromocytoma in which surgery is contraindicated. It can be useful in patients whose condition is refractory to phenoxybenzamine therapy, or it can be administered as an adjunct to that therapy.

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