5-(aminosulfonyl)-4-chloro-2-[(2-furanylmethyl)amino]benzoic acid

Absorption
Mean bioavailability is 64% with the tablet and 60% with the oral solution.

Distribution
Protein binding is 91% to 99% (albumin).

Metabolism
The major metabolite is furosemide glucuronide.

Elimination
The t 1/ 2 is about 2 h; furosemide is excreted in urine.

Onset
PO 1 h, IV 5 min.

Peak
PO 1 to 2 h, IV 30 min.

Duration
PO 6 to 8 h, IV 2 h.

Aminoglycosides, ethacrynic acid
May increase auditory toxicity. Avoid coadministration.

Antihypertensive agents
Antihypertensive effects may be potentiated. Reduce dose by at least 50% when furosemide is coadministered.

Charcoal
May reduce absorption of furosemide.

Cisplatin
May cause additive ototoxicity.

Digitalis glycosides
Electrolyte disturbances may predispose to digitalis-induced arrhythmias.

Lithium
May increase plasma lithium levels and toxicity. Avoid coadministration.

Norepinephrine
Arterial responsiveness to norepinephrine may be decreased.

NSAIDs
May decrease effects of furosemide.

Phenytoin
May reduce diuretic effects of furosemide.

Salicylates
Because of competition for renal excretion, patients may experience salicylate toxicity. Salicylates may impair diuretic response in patients with cirrhosis and ascites.

Succinylcholine
The effects may be potentiated by furosemide.

Sucralfate
Natriuretic and antihypertensive effects of furosemide may be decreased; separate the administration times by at least 2 h.

Thiazide diuretics
Synergistic effects that may result in profound diuresis and serious electrolyte abnormalities.

Tubocurarine
The skeletal muscle relaxant effect may be antagonized by furosemide.

Incompatibility
Acid solutions including other parenteral medications (eg, labetalol, ciprofloxacin, amrinone, milrinone): do not add to furosemide solution; precipitate forms.