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Pheochromocytoma...In Search for ideal agent




A common initial approach has been to use phenoxybenzamine for long-term alpha  blockade.



Preoperative preparation should include 1–2 weeks of alpha -adrenergic–blocker.
Volume replacement is important when starting alpha blockers
and patients often have a decreased Hematocrit after beginning therapy
Preoperative treatment with phenoxybenzamine results in a significantly smoother course than in untreated patients.
This drug has a long half-life (approximately 12 hours) and is highly lipid soluble.
The starting dosage is 10– 20 mg daily in 2 doses. Every 3–4 days the dose is increased until either no marked symptoms of catecholamine excess are evident or the patient complains  of side effects from postural hypotension and/or a stuffy nose, with a final dosage range of 40–100 mg/d.

There are several disadvantages to the use of phenoxybenzamine
Adequate volume expansion after institution of the drug may take as long as 2–3 weeks. Thus, patients presenting for surgery who have been on phenoxybenzamine for a shorter time period should have their hypovolemia corrected preoperatively.
Alpha Blockade with phenoxybenzamine is irreversible and depends  on synthesis of alpha receptors
Thus, there may be continued alpha blockade following tumor removal, which can contribute to postoperative hypotension.

Prazosin and Doxazosin (selective alpha receptors blockers) have   been used with success for PREOP PREPARATION
The rationale behind their selection is a shorter duration of action providing easier dose adjustment and potentially decreasing the postoperative hypotension period. Reflex tachycardia is decreased because the presynaptic alpha receptors not blocked ...

Calcium channel blockers also have been advocated for preoperative and intraoperative blood pressure control in patients with pheochromocytomas.

In Comaprison to alpha blockers  calcium channel blockers do not produce orthostatic or overshoot hypotension.
In addition, therapy may be started as late as 24 hours prior to surgery and optimal cardiovascular effects are still obtained.
Several reports suggest that calcium channel blockers may be the drug of choice for antihypertensive therapy during preoperative preparation of the pheochromocytoma patient.

Bravo EL. Pheochromocytoma: an approach to antihypertensive management. Ann NY Acad Sci 2002;970:1–10.

Sparks WJ, Seefelder C, Shamberger R, et al. The perioperative management of a patient with complex single ventricle physiology and pheochromocytoma. Anesth Analg 2005;100:972–975.

Janetschek G, Neumann HP. Laparoscopic surgery for pheochromocytoma. Urol Clin North Am 2001;28:97–105




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