Diuretic Medications for NCLEX: Loop, Thiazide, Potassium-Sparing & Osmotic
Review all diuretic drug classes for the NCLEX exam. Learn mechanisms, electrolyte effects, and nursing considerations for each diuretic type.
Diuretic Medications: NCLEX Pharmacology Review
Diuretics are among the most commonly prescribed medications and a frequently tested topic on the NCLEX. Understanding the different classes, their mechanisms, electrolyte effects, and nursing considerations is essential.
Loop Diuretics
Loop diuretics (furosemide/Lasix, bumetanide/Bumex) are the most potent diuretics, acting on the ascending loop of Henle. They inhibit sodium, potassium, and chloride reabsorption, producing significant diuresis. Used for heart failure, pulmonary edema, and acute fluid overload. Key side effects include hypokalemia, hyponatremia, hypocalcemia, hypomagnesemia, dehydration, and ototoxicity (especially with rapid IV administration). Monitor potassium levels closely and encourage potassium-rich foods (bananas, oranges, potatoes). Administer in the morning to prevent nocturia.
Thiazide Diuretics
Thiazide diuretics (hydrochlorothiazide/HCTZ, chlorthalidone) act on the distal convoluted tubule. They are first-line treatment for essential hypertension. Side effects include hypokalemia, hyperglycemia, hyperuricemia (can trigger gout), and hypercalcemia. Note that thiazides increase calcium reabsorption, which differentiates them from loop diuretics that waste calcium. Monitor glucose levels in diabetic patients as thiazides can worsen glycemic control.
Potassium-Sparing Diuretics
Potassium-sparing diuretics include spironolactone (Aldactone), amiloride, and triamterene. Spironolactone is an aldosterone antagonist also used in heart failure. These diuretics have a weak diuretic effect but preserve potassium. The primary concern is hyperkalemia. Do not combine with ACE inhibitors, ARBs, or potassium supplements without careful monitoring. Spironolactone can cause gynecomastia in males and menstrual irregularities in females due to antiandrogenic effects.
Osmotic Diuretics
Mannitol is the primary osmotic diuretic, used to reduce intracranial pressure and intraocular pressure. It works by creating an osmotic gradient that pulls water from tissues into the vascular space. Administer through a filter needle as crystals may form. Monitor serum osmolality and neurological status. Review more with our pharmacology flashcards and test yourself at pharmacology mini-exams.