Preoperative Alpha Blockade for Pheochromocytoma

Study Overview
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Brief Summary
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Pheochromocytoma is a rare, catecholamine (ex. adrenaline) secreting tumor that requires preoperative alpha blockade to minimize intraoperative hemodynamic instability, thereby reducing intra- and postoperative morbidity and mortality. Phenoxybenzamine is a non-selective alpha blocker that is significantly more expensive and is associated with increased adverse effects in comparison with selective alpha blockers such as doxazosin. Retrospective studies show minimal differences in hemodynamic instability and no differences in postoperative morbidity and mortality between selective vs. non-selective alpha blockers. This study is a randomized controlled trial that will compare hemodynamic instability, morbidity, mortality, cost, and quality of life between patients blocked with phenoxybenzamine vs. doxazosin.

Detailed Description
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Pheochromocytoma is a catecholamine (ex. adrenaline) secreting tumor for which the primary treatment is surgical resection. Due to the hormones secreted by the tumor, alpha receptors on peripheral blood vessels are activated, causing constriction of these blood vessels and dangerously high blood pressure. During resection of the tumor, the source of excess hormone secretion is abruptly removed, which can lead to life-threatening blood pressure fluctuations during surgery. Alpha blockers are a class of medication that blocks the alpha receptor on blood vessels. Given preoperatively over a few weeks, these medications negate the effects of the excess hormones secreted by the pheochromocytoma, reducing the frequency and severity of dangerous blood pressure fluctuations intraoperatively and postoperatively. Preoperative alpha blockade is therefore critical to safely perform surgery to resect pheochromocytoma. Phenoxybenzamine, a non-selective alpha blocker, is the most common medication used to alpha block patients prior to pheochromocytoma resection. However, due to increasing drug costs and increased side effects in comparison with selective alpha blockers, there is a renewed interest in studying alternatives to phenoxybenzamine. Selective alpha blockers such as doxazosin are also commonly used to alpha block patients prior to pheochromocytoma resection. Selective alpha blockers are significantly less expensive and are associated with fewer side effects than phenoxybenzamine. Most retrospective studies comparing phenoxybenzamine with selective alpha blockers show no difference in intraoperative blood pressure fluctuations, morbidity, or mortality in pheochromocytoma resection. However, no prospective, randomized controlled trials comparing phenoxybenzamine to selective alpha blockers have been performed. The purpose of our study is to analyze preoperative, intraoperative, and postoperative outcomes in patients randomized to receive phenoxybenzamine (non-selective) or doxazosin (selective) for alpha blockade prior to pheochromocytoma resection. Outcomes will include postoperative morbidity and mortality, intraoperative hemodynamic instability, quality of life, and cost.

Official Title
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Randomized Controlled Trial of Preoperative Alpha Blockade for Pheochromocytoma

Conditions
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Pheochromocytoma, Paraganglioma

Intervention / Treatment
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* Drug: Phenoxybenzamine
* Drug: Doxazosin


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adults with pheochromocytoma / paraganglioma undergoing surgical resection Exclusion Criteria: Children < 18 years

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Phenoxybenzamine<br>3-4 weeks prior to date of surgery, patient will start phenoxybenzamine 10mg PO twice daily. Phenoxybenzamine will then be titrated to a blood pressure <120/80 (sitting) with mild orthostatic hypotension (drop in systolic blood pressure by 20 points or diastolic blood pressure by 10 points from sitting to standing position); systolic blood pressure not less than 90 (standing). | Drug: Phenoxybenzamine<br>* Non-selective alpha blocker<br>* Other names: Dibenzyline;|
| Experimental: Doxazosin<br>3-4 weeks prior to date of surgery, patient will start doxazosin 1 mg PO daily. Phenoxybenzamine will then be titrated to a blood pressure <120/80 (sitting) with mild orthostatic hypotension (drop in systolic blood pressure by 20 points or diastolic blood pressure by 10 points from sitting to standing position); systolic blood pressure not less than 90 (standing). | Drug: Doxazosin<br>* Selective alpha blocker<br>* Other names: Cardura;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Hemodynamic Instability | Proportion of operative time outside target thresholds: SBP >180 or <80; DBP > 90; MAP>150 or <50; HR>90. Arterial line blood pressure measurements were extracted from the electronic medical record every 60 seconds. | Intraoperative, approximately 90 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mortality | Death within 30 days of surgery | 30 days postoperatively | 
| Daily Cost of Drug |  | Preoperative (2-3 weeks prior to surgery) | 
| Quality of Life- Physical Functioning, Role Limitations Due to Physical Problems, Bodily Pain, General Health Perceptions, Vitality, Social Functioning, Role-limitations Due to Emotional Problems, and Mental Health | Patients will take the SF-36 as well as a symptom survey describing the frequency and impact on their quality of life at several time points including prior to starting alpha blockade, immediately prior to surgery after being sufficiently blocked, and postoperatively at 30 days, 3 months, 6 months, and 1 year | From date of surgery (-2 to 3 weeks, -1 day, 30 days, 3 months, 6 months, 1 year) | 
| Morbidity as Assessed by Occurrence of Adverse Events | Morbidity will be graded by Clavien Classification of adverse events | Postoperatively during inpatient stay and during readmissions up to 30 days postoperatively | 
| Participants Admitted to Post-operative Intensive Care Unit (ICU) |  | up to 30 days post-surgery |