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CHICAGO -- Two drugs used to prepare patients for resection of pheochromocytoma (PCC) appeared safe for controlling perioperative hemodynamics when compared with each other, according to researchers reported here.

Intraoperative time outside the blood pressure target range (primary endpoint) was 12% with doxazosin and 11% with phenoxybenzamine (P=0.75), according to Edward Buitenwerf, MD, of the University of Groningen in the Netherlands, and colleagues.

"The results of this randomized open-label clinical trial demonstrate an equal efficacy of pretreatment with either drug in intraoperative hemodynamic control during pheochromocytoma resection," Buitenwerf's group stated at ENDO 2018. "Patients pre-treated with phenoxybenzamine required more β-blockers preoperatively, presumably via enhanced reflex tachycardia, but fewer vasodilation agents during surgery."

The authors enrolled patients undergoing surgery for pheochromocytoma (ages ≥18 years) who were randomized to pretreatment with either drug. Preoperative blood pressure targets were <130/80 mmHg (supine), and systolic BP 90-110 mmHg (upright). β-blockers were added if heart rate was >80/min (supine) or >100/min (upright), they noted.

Anesthetic procedures were standardized, and the primary endpoint was "the percentage of intraoperative time outside the blood pressure target range (i.e. MAP<60 mmHg and systolic BP>160 mmHg)," they wrote.

The study population consisted of 134 patients, about age 54, and 52% were female. Pretreatment (median of 14 days before surgery) with doxazosin was given to 68 patients at a dose of 40 mg while pretreatment with phenoxybenzamine was given to 66 patients at a dose of 120 mg. The mean BMI was about 25, and about 25% of the patients were current smokers.

The authors reported that on all parameters of clinical outcomes, there did not appear to be any statistically significant differences:

• Incidents of hypotension: 38% of patients on doxazosin versus 39% of patients on phenoxybenzamine (P=1.00)
• Incidents of hypertension: 13% vs 26% (P=0.110)
• Length of ICU: median 1 day for both arms (P=0.778)
• Length of stay in hospital: median 14 days for both arms (P=0.895)
• Cardiovascular morbidity: 6% in both arms (P=1.00)
• Cardiovascular mortality did not occur in any of the patients in the study (P=1.00)

"The results of this study are going to give me more confidence in use of these drugs when I prepare patients for these surgeries," said Tobi Else, MD, of the University of Michigan in Ann Arbor. "The researchers should be congratulated that they were able to find 134 patients with these extremely rare tumors, which affect production of adrenaline and noradrenaline and give you high blood pressure, high heart rate, and sweating which can be a challenge during surgery."

"In surgery you want to have everything stable, and that's why we give these patients medications to block any effect of adrenaline/noradrenaline, and what has been used is phenoxybenzamine or doxazosin," Else, who was not involved in the study, told MedPage Today.

He pointed out that there is a cost difference, as phenoxybenzamine is more expensive than doxazosin. "I use a lot of doxazosin, which costs pennies, in these surgeries and this study gives me a little more confidence that is a safe agent," Else stated.

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