Diuretics Flashcards
Mannitol
Action: Osmotic agent; ↑ nephron osmolarity in PCT and thin descending limb of Henle; increases excretion of water more than sodium.
Uses: ↓ intracranial/intraocular pressure; drug overdose.
Toxicity: Pulmonary edema (increase ECF); dehydration.
Other: Freely filtered through glomerulus; excreted unchanged in 30-60 minutes.
Acetazolamide (Diamox)
Action: Inhibitor of carbonic anhydrase in PCT; blocks reabsorbsion of bicarbonate.
Uses: Glaucoma (decreases production of aqueous humor); metabolic alkalosis; elimination of acidic toxins; acute mountain sickness (stimulates ventilation via metabolic acidosis).
Toxicity: Hyperchloremic metabolic acidosis; paresthesias; sulfa allergy; renal stones; potassium wasting.
Other: HCO3- + H+ → H2CO3 → H2O + CO2.
Other Drugs in Class: Dorzolamide; brinzolamide.
Furosemide (Lasix)
Action: Inhibit Na+/K+/2Cl- co-transporter (NKCC2) in thick ascending limb of Henle; decreased positive luminal potential leads to increased excretion of calcium and magnesium.
Uses: Edema in CHF, cirrhosis and nephrotic syndrome; HTN; hypercalcemia; hyperkalemia; ARF.
Toxicity: Hyperkalemic metabolic alkalosis; ototoxicity; dehydration; hyperuricemia; hypermagnesemia; allergic reaction (sulfa).
Other: “High ceiling diuretic”; rapid onset of action (minutes).
Other Drugs in Class: Bumetanide; ethacrynic acid.
Hydrochlorothiazide (Microzide)
Action: Thiazide diuretic; inhibit Na+/Cl- co-transporter (NCC) in DCT.
Uses: First-line for treatment of HTN, CHF, idiopathic hypercalcinurea, nephrosis, and nephrogenic DI.
Toxicity: Dehydration; hypokalemic metabolic alkalosis; hyponatremia; hyperlipidemia; hyperuricemia; hypercalcemia; hyperglycemia; allergic reactions (sulfa).
Other: “Low ceiling diuretic”; component of many combination therapies.
Other Drugs in Class: Metolazone.
Amiloride (Midamor)
Action: Potassium-sparing diuretic; inhibit Na+ channel (ENaC) in cortical collecting duct; positively charged lumen decreases K+ excretion.
Uses: Used in combination with loop and thiazide diuretics to prevent hypokalemia; CHF; HTN.
Toxicity: Hyperkalemia; hyperchloremic metabolic acidosis; impotence (males); abnormal mensus (females).
Other Drugs in Class: Triamterene.
Spironolactone (Aldactone)
Action: Potassium-sparing diuretic; competitive antagonist of aldosterone (MC) receptor in CCD; reduces quantity of Na+ channel (ENaC) and K+ channel (ROMK).
Uses: Primary (Conn syndrome) and secondary (edematous states caused by cirrhosis, nephrotic syndrome and CHF) hyperaldosteronism; HTN; polycystic ovary syndrome (PCOS); hirsutism; used in combination with loop diuretics or thiazides to prevent hypokalemia.
Toxicity: Hyperkalemia; hyperchloremic metabolic acidosis; endocrine effects (i.e. gynecomastia); impotence (males); abnormal mensus (females).
Other Drugs in Class: Eplerenone (lacks anti-androgen effects).
Tolvaptan (Samsca)
Action: V2 vasopressin receptor antagonist in CCD; lowers quantitiy of water channels in apical membrane = water wasting.
Uses: Symptoms of inappropriate anti-diuretic hormone (SIADH); hyponatremia.
Toxicity: Nephrogenic diabetes insipidus; hepatotoxicity; GI upset.
Other: In clinical trials for CHF and polycystic kidney disease.
