A female client with a history of pheochromocytoma is admitted to the hospital in an acute hypertensive crisis. To reverse hypertensive crisis caused by pheochromocytoma, nurse Lyka expects to administer:
A. mannitol (Osmitrol)
B. methyldopa (Aldomet)
C. phentolamine (Regitine)
D. felodipine (Plendil)
Correct Answer: C. phentolamine (Regitine)
Pheochromocytoma causes excessive production of epinephrine and norepinephrine, natural catecholamines that raise the blood pressure. Phentolamine, an alpha-adrenergic blocking agent given by I.V. bolus or drip, antagonizes the body’s response to circulating epinephrine and norepinephrine, reducing blood pressure quickly and effectively.
Option A: Mannitol, a diuretic, isn’t used to treat hypertensive emergencies. Mannitol can be used for the reduction of intracranial pressure and brain mass, to reduce intraocular pressure if this is not achievable by other means, to promote diuresis for acute renal failure to prevent or treat the oliguric phase before irreversible damage, and to promote diuresis to promote excretion of toxic substances, materials, and metabolites.
Option B: Although methyldopa is an antihypertensive agent available in parenteral form, it isn’t effective in treating hypertensive emergencies. Methyldopa is a medication used in the management and treatment of hypertension. It is in the centrally acting anti-hypertensive class of drugs.
Option D: Felodipine, an antihypertensive agent, is available only in extended-release tablets and therefore doesn’t reduce blood pressure quickly enough to correct hypertensive crisis. Felodipine is an agent in the dihydropyridine class of calcium channel blockers. Felodipine is FDA approved and indicated in the treatment of essential hypertension. Reduction in blood pressure lowers the risk of cardiovascular morbidity and mortality.
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