====== Furosemide (Lasix®) ======<WRAP right 340px><WRAP infobox>| | {{ :cardio:diuretics:furosemide_structure.svg |}} |^ Furosemide || Brand Names | Lasix® || Drug Class | [[cardio:diuretics:loop:start|Loop Diuretic]] || Primary Indications | [[cardio:heart_failure:start|Heart Failure]]; Pulmonary edema; Volume overload; CKD edema || Blood Pressure Effect | ↓ preload, ↓ BP || Mortality Benefit | No (symptom relief) || Elimination | Renal || Black Box Warning | Ototoxicity (high dose/rapid IV) || FDA Approval | 1966 |</WRAP></WRAP>===== Overview =====Furosemide is a potent loop diuretic that blocks NKCC2 in the thick ascending limb, producing brisk natriuresis and diuresis. It is first-line for acute decompensated heart failure and volume overload.<WRAP clear></WRAP>----===== Mechanism of Action =====**Primary Molecular Target**  * Na-K-2Cl cotransporter (NKCC2) in thick ascending limb**Segment Effects**  * ↓ NaCl reabsorption in TAL  * ↑ Ca2+ and Mg2+ excretion  * Disrupts medullary concentrating gradient**Net Physiologic Outcomes**  * Powerful diuresis  * ↓ preload and pulmonary congestion  * Rapid symptom relief in volume overload----===== Indications =====  * Acute pulmonary edema  * Decompensated heart failure  * Edema in CKD/cirrhosis/nephrotic syndrome  * Severe hypertension with volume overload----<WRAP blackbox>===== Black Box Warning =====Risk of profound diuresis, electrolyte depletion, and ototoxicity with high doses or rapid IV administration.</WRAP>----<WRAP contra>===== Contraindications =====Absolute:  * Anuria  * Severe sulfonamide allergy (rare)Relative / Caution:  * Hypovolemia  * Severe electrolyte depletion  * Gout</WRAP>----<WRAP details>===== Dosing =====Heart failure/edema:  * PO: 20–80 mg daily or BID (titrate)  * IV: 20–40 mg, repeat as neededRenal adjustment:  * Higher doses often required in CKD</WRAP>----<WRAP details>===== Pharmacokinetics =====Absorption:  * Oral/IVBioavailability:  * ~50% (variable)Metabolism:  * Minimal hepaticHalf-life:  * ~2 hoursElimination:  * Renal</WRAP>----<WRAP details>===== Adverse Effects =====Common:  * Hypokalemia  * Hypomagnesemia  * Polyuria  * HypotensionSerious:  * Ototoxicity  * AKI from overdiuresis  * Hyponatremia</WRAP>----<WRAP details>===== Drug Interactions =====Increased risk:  * Digoxin toxicity (via hypokalemia)  * NSAIDs (↓ diuretic effect)  * Lithium (↑ levels)Avoid combination:  * Aminoglycosides (ototoxicity risk)</WRAP>----<WRAP monitoring>===== Monitoring =====Labs:  * Electrolytes (K+, Mg2+, Na+)  * CreatinineVitals:  * Blood pressure  * WeightClinical:  * Volume status  * Hearing changes (high dose)</WRAP>----<WRAP pearls>===== Clinical Pearls =====  * Most potent class of diuretics  * Useful in acute pulmonary edema  * Causes hypocalcemia (unlike thiazides)</WRAP>----===== Comparison Within Class =====Compared to other [[cardio:diuretics:loop:start|loop diuretics]]:  * Shorter half-life than torsemide  * Variable oral bioavailability  * Rapid onset when IV----===== Related =====  * [[cardio:diuretics:loop:start|Loop Diuretics]]  * [[cardio:heart_failure:start|Heart Failure]]  * [[cardio:diuretics:start|Diuretics]]