Pheochromocytoma: A review on preoperative treatment with phenoxybenzamine or doxazosin

Background: During surgical treatment of pheochromocytoma, haemodynamic instability may occur. To prevent this, patients receive preoperative treatment with an alpha-blocker. Nowadays, some centres use phenoxybenzamine, while others use doxazosin. The purpose of this review is to analyse the current evidence of the benefits and risks of phenoxybenzamine and doxazosin in the preoperative treatment of pheochromocytoma. Methods: The literature was reviewed by searching PubMed using the following search terms: pheochromocytoma, phenoxybenzamine, doxazosin and alpha-blockade. The filter was set on English language. Results: No randomised controlled trials were found. Five follow-up studies comparing phenoxybenzamine and doxazosin in the treatment of pheochromocytoma were retrieved and analysed. There was a trend that systolic arterial pressure is slightly better controlled by phenoxybenzamine. However, this resulted in more pronounced postoperative hypotension as well. The use of an alpha-blocker was often accompanied by other vasoactive agents. Phenoxybenzamine was often accompanied by a beta-blocker to control reflex tachycardia, while patients on doxazosin received significantly more additional antihypertensive medicines. Most of the studies showed that the use of vasoactive drugs and fluid infusion does not differ significantly between the two drugs. Phenoxybenzamine caused significantly more orthostatic hypotension, oedema and complaints of a stuffy nose. Conclusion: On the basis of the current evidence, there is no evidently superior alpha-blocker for the pretreatment of patients with pheochromocytoma. Perioperative haemodynamics seem to be slightly better controlled with phenoxybenzamine, at the cost of more pronounced postoperative hypotension. Side effects occurred less often in the doxazosin group.