What is the initial treatment for a patient with pheochromocytoma?

From the Guidelines

The initial treatment for a patient with pheochromocytoma is alpha-adrenergic blockade, typically with doxazosin or terazosin, followed by a beta-blocker, to control hypertension and prevent catecholamine-induced complications, as recommended by the most recent guidelines 1.

Key Considerations

• The goal of preoperative management is to normalize blood pressure, control tachycardia, restore blood volume, and prevent paroxysmal hypertensive episodes.
• Alpha blockers such as doxazosin (2-8 mg daily) or terazosin should be initiated 1-3 weeks before surgery to prevent a catecholamine surge intraoperatively 1.
• Beta-blockers may be added after adequate alpha blockade is established, but never before, as unopposed alpha stimulation can worsen hypertension.
• Adequate fluid administration should be carefully managed to prevent profound hypotension, particularly right after tumor excision 1.

Treatment Options

• Doxazosin or terazosin can be used as first-line alpha blockers, with the advantage of having fewer side effects compared to phenoxybenzamine.
• Beta-blockers such as propranolol (20-40 mg three to four times daily) can be added to control reflex tachycardia.
• Calcium channel blockers like amlodipine (5-10 mg daily) can also be used as adjunctive therapy.

Importance of Preoperative Management

• Surgical removal of the tumor without adequate blockade can trigger a life-threatening hypertensive crisis due to the sudden release of catecholamines during manipulation of the tumor.
• Preoperative medical management is crucial to prevent catecholamine-induced complications and ensure a safe surgical procedure 1.

From the FDA Drug Label

Metyrosine is indicated in the treatment of patients with pheochromocytoma for: 1. Preoperative preparation of patients for surgery 2. Management of patients when surgery is contraindicated 3. Chronic treatment of patients with malignant pheochromocytoma In patients with pheochromocytoma, who produce excessive amounts of norepinephrine and epinephrine, administration of 1 to 4 grams of Metyrosine per day has reduced catecholamine biosynthesis from about 35% to 80% as measured by the total excretion of catecholamines and their metabolites

The initial treatment for a patient with pheochromocytoma is preoperative preparation with metyrosine for patients undergoing surgery, or management with metyrosine when surgery is contraindicated, or chronic treatment with metyrosine for patients with malignant pheochromocytoma 2.

• The goal of treatment is to reduce catecholamine biosynthesis, which can be achieved with metyrosine doses of 1 to 4 grams per day.
• Treatment with metyrosine can decrease the frequency and severity of hypertensive attacks and lower blood pressure in most patients 2.

From the Research

Initial Treatment for Pheochromocytoma

The initial treatment for a patient with pheochromocytoma typically involves preoperative preparation with alpha-adrenergic blockers to control blood pressure and prevent hemodynamic instability during surgery.

• The use of phenoxybenzamine, a nonselective alpha-blocker, is commonly recommended for preoperative treatment of pheochromocytoma 3, 4, 5, 6.
• Doxazosin, a selective alpha-blocker, may also be used as an alternative to phenoxybenzamine, with some studies suggesting similar efficacy 7, 5, 6.
• The choice of alpha-blocker may depend on various factors, including the patient's specific condition, the surgeon's preference, and the availability of the medication.

Preoperative Preparation

Preoperative preparation with alpha-blockers is crucial to prevent hemodynamic instability during surgery.

• Phenoxybenzamine has been shown to be effective in controlling blood pressure and reducing the risk of complications during surgery 3, 4.
• Doxazosin may also be effective in controlling blood pressure, but its use may be associated with a higher risk of postoperative hypotension 6.
• The use of alpha-blockers may be accompanied by other vasoactive agents, such as beta-blockers, to control reflex tachycardia 6.

Comparison of Alpha-Blockers

Several studies have compared the efficacy of phenoxybenzamine and doxazosin in the preoperative treatment of pheochromocytoma.

• One study found that phenoxybenzamine may blunt intraoperative hypertension better than doxazosin, but this difference did not translate to fewer cardiovascular complications 5.
• Another study found that systolic arterial pressure was slightly better controlled by phenoxybenzamine, but this resulted in more pronounced postoperative hypotension 6.
• Overall, the current evidence suggests that there is no evidently superior alpha-blocker for the pretreatment of patients with pheochromocytoma, and the choice of alpha-blocker should be individualized based on the patient's specific needs and circumstances 6.