Phenoxybenzamine Hydrochloride (Brand Name: Dibenzyline) is FDA approved to treat high blood pressure and sweating associated with pheochromocytoma. It is a nonselective blocker of alpha- receptors taken twice daily as a capsule. A pheochromocytoma is a neuroendocrine tumor that arises from cells that produce epinephrine, norepinephrine, and dopamine. Symptoms of pheochromocytoma include episodic headache, sweating, hypertension and tachycardia and can be provoked by use of medications associated with certain adverse effects. Patient medications lists should be evaluated for possible offending medications.

The preferred treatment option for pheochromocytoma is surgical resection of the tumor, if anatomically possible. To prepare patients for surgery, alpha blockade combined with beta-adrenergic blockade should be initiated 10-14 days prior to surgery to control blood pressure and prevent intraoperative hypertensive crisis. In addition to phenoxybenzamine, doxazosin, terazosin, and prazosin are effective alpha blocking medications to treat pheochromocytoma. If surgery is contraindicated it may be necessary to initiate long term alpha blockade and beta-adrenergic blockade to control hypertension and sweating. Long term use of phenoxybenzamine is not recommended. Providers must carefully weigh the risks and benefits before use.

Definitions

Neuroendocrine tumor is a rare type of tumor that arises from specialized body cells called neuroendocrine cells. These cells have traits of both nerve cells and hormone-producing cells, and release hormones into the blood in response to signals from the nervous system.

Intraoperative hypertensive crisis is severely elevated blood pressure that occurs during surgery.

Medical Necessity Criteria for Initial Authorization

The Plan considers phenoxybenzamine (Dibenzyline) medically necessary when ALL of the following criteria are met:

1. The member has a documented diagnosis of pheochromocytoma; AND
2. The medication is being prescribed by or in consultation with an endocrinologist or a physician who specializes in the management of pheochromocytoma; AND
3. The medication is being used for ONE (1) of the following:
   • as preoperative preparation for a scheduled surgical resection within 14 days of phenoxybenzamine initiation; or
   • for prolonged (long-term) treatment of hypertension caused by a pheochromocytoma not amenable to surgery; AND
4. The member is unable to use or has tried and failed TWO (2) of the following selective alpha blockers:
   • Doxazosin; and/or
   • Prazosin; and/or
   • Terazosin; AND
5. Chart documentation and supporting laboratory test results are provided for review to substantiate the above listed requirements.

If the above prior authorization criteria are met, phenoxybenzamine will be approved for:

• 14 days for pre-operative management; OR
• 12 months for long-term management

Medical Necessity Criteria for Reauthorization

Reauthorization for 12 months will be granted if recent chart documentation (within the last 12 months) shows the member has experienced therapeutic response to the requested medication as evidenced by ONE (1) of the following:

1. clinical improvement (e.g., management of the signs and symptoms of pheochromocytoma) in symptoms since starting the requested medication; OR
2. disease stability (e.g., control of tachycardia) since starting the requested medication

Experimental or Investigational / Not Medically Necessary

phenoxybenzamine (Dibenzyline) for any other indication is considered not medically necessary by the Plan, as it is deemed to be experimental, investigational, or unproven.

Table 1: ICD-10-CM (diagnosis) Codes for Pheochromocytoma

• C74.9 Malignant neoplasm of adrenal gland, unspecified
• C75.9 Malignant neoplasm of endocrine gland, unspecified
• Adrenomedullary hyperfunction

References

1. Dibenzyline (phenoxybenzamine) [prescribing information]. St. Michael, Barbados: Concordia Pharmaceuticals Inc; April 2020.
2. Kinney MA, Narr BJ, and Warner MA, 'Perioperative Management of Pheochromocytoma,' J Cardiothorac Vasc Anesth, 2002, 16(3):359-69.
3. Kocak S, Aydintug S, Canakci N. Alpha blockade in preoperative preparation of patients with pheochromocytomas. International Surgery. 2002;87(3):191-194. Accessed at: https://pubmed.ncbi.nlm.nih.gov/12403097/
4. Lenders JWM, et al. Pheochromocytoma and Paraganglioma: An Endocrine Society Clinical Practice Guideline, The Journal of Clinical Endocrinology & Metabolism, Volume 99, Issue 6, 1 June 2014, p1915–1942, https://doi.org/10.1210/jc.2014-1498
5. National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology, Neuroendocrine and Adrenal Tumors. Version 2.2021. June 18, 2021
6. Romero M, Kapur G, Baracco R, Valentini RP, Mattoo TK, Jain A. Treatment of hypertension in children with catecholamine-secreting tumors: a systematic approach. J Clin Hypertens (Greenwich). 2015;17(9):720-725. doi: 10.1111/jch.12571
7. Young WF, Kebebew E. Treatment of pheochromocytoma in adults. Accessed via UpToDate. Last updated Feb 12, 2021. Accessed July 14, 2021.

Clinical Guideline Revision / History Information

• Original Date: 11/05/2020
• Reviewed/Revised: 10/14/2021, 12/01/2021, 9/15/2022, 9/21/2023