What Is Furosemide?

 I . Pharmacologic Category

– Antihypertensive, Diuretic,Loop

II. Posology

Furosemide 40 mg = bumetanide 1 mg = torsemide 20mg
 Ascites, Cirrhosis :
– Could use a combination with spironolactone. Spironolactone 100mg to furosemide 40 mg.
– Oral: initial 40mg once daily, maximum dose: 160mg once daily, for small volume ascites and weight less than 50 kg, some experts recommend a starting dose of 20mg once daily.
 Edema ( pulmonary, or peripheral edema )
– Naive to loop diuretics: Oral or IV initial dose 20 to 40 mg once then titrate as needed to an effective dose.
– Refractory edema or acute decompensation in patients taking oral diuretics: IV bolus /intermittent dosing: initial 1 to 2.5 times the total daily oral maintenance dose once can be given 80 mg to 200 mg IV as an initial bolus)
– Continuous infusion :
 eGFR  ≥ 30 ml /mn/1.73 m² : IV initial 5 mg/h , if not adequate, repeat IV bolus and increased continuous infusion to 10mg/h, continue to bolus and titrate infusion as needed up to 40 mg/hour
 eGFR < 30 ml /mn/ 1.73 m² : initial 20 mg/hour , if not adequate, repeat IV bolus dose and increased continuous infusion to 40 mg/hour.
– Titration: if the initial dose does not adequate in diuresis, double the individual dose until diuresis occurs. Titration of an IV dose can occur at ≥ 2-hour intervals as needed in hospitalized patients. The maximum recommended total daily dose is 600 mg/day to avoid toxicity.
– Transitioning from IV to oral: some experts recommend giving 1 to 2 times the IV dose orally. For example, an IV dose of 80 mg/day should be converted to an oral dose of 80 to 160 mg/day in 1 to 2 divided doses.
 Dosing according to Renal Impairment: Adult
– Altered kidney function: IV oral,
 eGFR > 30 ml /mn/1.73m² : no dosage adjustment necessary
 eGFR < 30 ml/mn/1.73 m² : signle dose> 160 to 200 mg IV
– Hemodialysis,intermittent: IV or oral is useless for anuric patients
 Dosing according hepatic impairment : Adult
Monitor effects ,particulary with high doses
 Administration : Adult
Direct IV injections may be administered at a rate of 20 to 40 mg per minute, a high dose ≥ of 160 mg should be given as a short-term infusion of 4 mg/ min, exceeding this rate increases the risk of ototoxicity.

III. Indication
– Management of edema with heart failure, cirrhosis of the liver, and renal disease including nephrotic syndrome ( Oral, injection )
– Therapy for pulmonary edema
– Treatment of hypertension alone or combination with antihypertensive

IV. Adverse Reactions
-Acute kidney injury due to fluid loss
-Fluid/Electrolyte loss: hypovolemia and electrolyte loss. Electrolyte disturbances (eg, hypocalcemia, hypokalemia, hypomagnesemia) may cause the patient serious cardiac arrhythmias.
-Hypersensitivity reactions ( immediate and delayed ): angioedema, urticaria, and anaphylaxis
– Ototoxicity: hearing loss (deafness) and tinnitus, which is generally reversible(lasting from 30 mn to 24 h after administration

V. Contraindications 
Hypersensitivity to furosemide or any component of the formulation, anuria.

VI. Mechanism of action 
Inhibit reabsorption of Na and Cl in the ascending loop of Henle and proximal and distal renal tubules.

VII. Pharmacodynamics and Pharmacokinetics
The onset of action: 30 to 60 mn , symptomatic improvement with acute pulmonary edema: within 15 to 20 minutes, occurs prior to the diuretic effect. Peak effect Oral SL: 1 to 2 h, IV: 0.5h
Duration: IV 2 h, SL: 6 to 8 h, Protein binding: 91%-99% , Half-life elimination L normal renal funtion 0.5 to 2 h, end stage renal disease : 9 h