Name: Furosemide (Lasix)
Class: Diuretic (Loop Diuretic)
Mechanism: Blocks the Na+/K+/Cl- co-transporter in the apical membrane of the thick ascending limb of Henle’s loop ® excretion of urinary water, Na+, K+, Ca2+, & Mg2+. Also causes venous and renal vasodilation.
Absorption: Oral, IV. Takes effect in 20 min.
Dist.: Metabolism.:
Excretion, t½: 1-1.5 hr. Shorter duration than thiazides.
Toxicity/S.E.s: Hypokalemia (esp. dangerous if pt. is on digitalis), Ca2+ & Mg2+ depletion, Metabolismolic alkalosis, volume contraction, mild hyperglycemia, thiazide-like lipid changes, sulfonamide allergy cross-rxn, ototoxicity. C/i—pts. susceptible to volume contraction from excessive diuresis (e.g., elderly), and pts. susceptible to problems w/hypokalemia (e.g., cirrhosis, digitalis). Adverse rxn w/lithium, aminoglycosides. Altered doses of anti-diabetic agents required.
Utility: Diuresis for hypertension when a short-acting diuretic is indicated. Treat HTN refractory to thiazides. Very useful in conditions refractory to less potent diuretics (e.g., CHF, renal insufficiency, nephrotic synd.). Treat hypercalcemia.
Special Features: Most potent diuretics available. Can cause excretion of up to 20% of filtered Na+.