Furosemide (fyoor OH se mide)
U.S. Brand Names Lasix®
Index Terms Frusemide
Generic Available Yes
Pharmacologic Category Diuretic, Loop
Medication Safety Issues
may be confused with famotidine, finasteride,
fluconazole, FLUoxetine, fosinopril, loperamide, torsemide
may be confused with Esidrix®, Lanoxin®,
Lidex®, Lomotil®, Lovenox®, Luvox®, Luxiq®
Urex® [Australia] may be confused with Eurax® which is a brand name for crotamiton
in the U.S.
Urex® [Australia]: Brand name for methenamine
in the U.S.
Pregnancy Risk Factor C
breast milk/use caution
of edema associated with heart failure and hepatic or renal disease; acute pulmonary
edema; treatment of hypertension (alone or in combination with other antihypertensives)
of Action/Effect Inhibits reabsorption of sodium and chloride in the ascending loop
of Henle and distal renal tubule, interfering with
the chloride-binding cotransport system, thus causing
increased excretion of water, sodium, chloride, magnesium, and calcium
Hypersensitivity to furosemide or any component of the formulation; anuria
[U.S. Boxed Warning]: If given in
excessive amounts, furosemide, similar to other loop
diuretics, can lead to profound diuresis, resulting
in fluid and electrolyte depletion; close
medical supervision and dose evaluation are required. Watch for and correct
electrolyte disturbances; adjust dose to avoid dehydration. When electrolyte depletion
is present, therapy should not be initiated unless serum electrolytes,
especially potassium, are normalized. In cirrhosis, avoid electrolyte and
acid/base imbalances that might lead to hepatic encephalopathy.;
correct electrolyte and acid/base imbalances prior to initiation when hepatic
coma is present. Coadministration of antihypertensives may increase the risk of hypotension.
Monitor fluid status and
renal function in an attempt to prevent oliguria, azotemia, and reversible increases in BUN and creatinine; close medical supervision of aggressive diuresis is required. Rapid I.V. administration, renal
impairment, excessive doses, and concurrent use of other ototoxins
is associated with ototoxicity.
Asymptomatic hyperuricemia has been reported with use;
rarely, gout may precipitate. Photosensitization may occur.
Use with caution in
patients with prediabetes or diabetes mellitus; may
see a change in glucose control. Use with caution in patients with systemic
lupus erythematosus (SLE); may cause SLE exacerbation
or activation. Chemical similarities are present among sulfonamides, sulfonylureas, carbonic anhydrase
inhibitors, thiazides, and loop diuretics (except ethacrynic acid). A risk of cross-reaction exists in
patients with allergy to any of these compounds; avoid use when previous
reaction has been severe. Discontinue if signs of hypersensitivity are noted.
concomitant use of Furosemide with any of the
following: Ethacrynic Acid
Furosemide may decrease the levels/effects of: Lithium; Neuromuscular-Blocking Agents
levels/effects of Furosemide may be decreased by: Aliskiren; Bile Acid Sequestrants; Herbs
(Hypertensive Properties); Methylphenidate; Nonsteroidal
Anti-Inflammatory Agents; Phenytoin; Salicylates; Yohimbine
Furosemide may increase the levels/effects of: ACE Inhibitors; Allopurinol;
Ethacrynic Acid; Lithium; Neuromuscular-Blocking
Agents; RiTUXimab; Salicylates
levels/effects of Furosemide may be increased by: Corticosteroids (Orally Inhaled); Corticosteroids
(Systemic); Diazoxide; Herbs (Hypotensive
Properties); Prostacyclin Analogues
Food: Furosemide serum levels may be decreased if taken with
Herb/Nutraceutical: Avoid bayberry, blue cohosh,
cayenne, ephedra, ginger, ginseng (American), kola, licorice (may worsen hypertension). Avoid black cohosh, California poppy, coleus, golden seal, hawthorn,
mistletoe, periwinkle, quinine, shepherd's purse (may
increase antihypertensive effect).
Adverse Reactions Frequency not defined.
hypotension, chronic aortitis, necrotizing angiitis, orthostatic hypotension, vasculitis
system: Dizziness, fever, headache, hepatic encephalopathy, lightheadedness, restlessness,
Dermatologic: Bullous pemphigoid, cutaneous vasculitis, erythema multiforme, exfoliative dermatitis, photosensitivity, pruritus, purpura, rash, urticaria
metabolic: Glucose tolerance test altered, gout, hyperglycemia, hyperuricemia, hypocalcemia, hypochloremia, hypokalemia, hypomagnesemia, hyponatremia,
Anorexia, constipation, cramping, diarrhea, nausea, oral and gastric
irritation, pancreatitis, vomiting
Urinary bladder spasm, urinary frequency
Hematological: Agranulocytosis (rare), anemia, aplastic
anemia (rare), hemolytic anemia, leukopenia,
Hepatic: Intrahepatic cholestatic
jaundice, ischemic hepatitis
Local: Injection site
pain (following I.M. injection), thrombophlebitis
skeletal: Muscle spasm, paresthesia, weakness
Otic: Hearing impairment (reversible or permanent with
rapid I.V. or I.M. administration), tinnitus
interstitial nephritis, fall in glomerular filtration
rate and renal blood flow (due to overdiuresis), glycosuria, transient rise in BUN
Anaphylaxis (rare), exacerbate or activate systemic lupus erythematosus
Onset of Action: Diuresis: Oral, S.L.: 30-60 minutes; I.M.: 30 minutes; I.V.:
improvement with acute pulmonary edema: Within 15-20 minutes; occurs prior to
Peak effect: Oral: 1-2 hours
of Action: Oral, S.L.: 6-8 hours; I.V.: 2 hours
Bioavailability: Oral tablet: 47-64%; Oral solution: 60%; S.L. administration of tablet:
~60%; results of a small comparative study (n=11) showed bioavailability of SL
administration of tablet was ~12% higher than oral administration of tablet (Haegeli, 2007).
Binding: 91% to 99%; primarily to albumin
Elimination: Normal renal function: 0.5-2 hours; End-stage renal
disease: 9 hours
Metabolism: Minimally hepatic
Excretion: Urine (Oral: 50%, I.V.: 80%) within 24 hours; feces (as unchanged drug);
nonrenal clearance prolonged with renal impairment
solution: 10 mg/mL
(2 mL, 4 mL, 10 mL)
solution [preservative free]: 10 mg/mL (2 mL, 4 mL,
oral: 10 mg/mL,
40 mg/5 mL
Tablet: 20 mg, 40 mg, 80 mg
Lasix®: 20 mg
Lasix®: 40 mg, 80 mg [scored]
Oral: Initial: 20-80 mg/dose; if response not adequate, may repeat the same dose or increase dose in
increments of 20-40 mg/dose at intervals of 6-8 hours; usual maintenance dose
interval is once or twice daily; may be titrated up to 600 mg/day with severe edematous
states. Note: May also be given on 2-4 consecutive days every week.
I.V.: Initial: 20-40 mg/dose; if
response not adequate, may repeat the same dose or increase dose in increments
of 20 mg/dose and administer 1-2 hours after previous dose (maximum dose: 200
mg/dose). Individually determined dose should then be given once or twice daily
although some patients may initially require dosing as frequent as every 6 hours.
Note: ACC/AHA 2009 guidelines for heart failure recommend a maximum single dose
of 160-200 mg.
I.V. infusion (Howard, 2001; Hunt, 2009): Initial: I.V. bolus dose 20-40 mg over 1-2 minutes, followed by
continuous I.V. infusion doses of 10-40 mg/hour. If urine output is <1 mL/kg/hour, double as necessary to a maximum of 80-160
mg/hour. The risk associated with higher infusion rates (80-160 mg/hour) must
be weighed against alternative strategies. Note:
ACC/AHA 2009 guidelines for heart
failure recommend 40 mg I.V. load, then 10-40 mg/hour infusion.
pulmonary edema: I.V.: 40 mg over 1-2 minutes. If response not adequate
within 1 hour, may increase dose to 80 mg. Note:
ACC/AHA 2009 guidelines for heart
failure recommend a maximum single dose of 160-200 mg.
resistant (Chobanian, 2003; JNC 7): Oral: 20-80 mg/day in 2 divided doses
heart failure: Oral,
I.V.: Doses up to 8 g/day have been
Elderly: Oral, I.M., I.V.: Initial: 20 mg/day; increase
slowly to desired response.
heart failure: Infants and Children:
Oral: Initial: 2 mg/kg/dose increased in increments of 1-2
mg/kg/dose with each succeeding dose at intervals of 6-8 hours until a
satisfactory response is achieved; maximum dose: 6 mg/kg/dose
I.V.: Initial: 1 mg/kg/dose; if
response not adequate, may increase dose in increments of 1 mg/kg/dose and
administer not sooner than 2 hours after previous dose, until a satisfactory
response is achieved; may administer maintenance dose at intervals of every 6-12
hours; maximum dose: 6 mg/kg/dose
resistant (unlabeled; AAP, 2004): Children
1-17 years: Oral: Initial: 0.5-2 mg/kg/dose once or twice daily;
maximum dose: 6 mg/kg/dose
Acute renal failure:
Doses up to 1-3 g/day may be necessary to initiate desired response; avoid use
in oliguric states.
Not removed by hemo- or peritoneal dialysis; supplemental dose is not
Impairment: Diminished natriuretic
effect with increased sensitivity to hypokalemia and
volume depletion in cirrhosis. Monitor effects, particularly with high doses.
Administer on an empty stomach
(Bard, 2004). May be administered with food or milk if GI distress occurs;
however, this may reduce diuretic efficacy.
I.V. injections should be given
slowly. In adults, undiluted direct I.V. injections may be administered at a
rate of 20-40 mg per minute; maximum rate of administration for short-term intermittent
infusion is 4 mg/minute; exceeding this rate increases the risk of ototoxicity. In children, a maximum rate of 0.5
mg/kg/minute has been recommended.
When I.V. or oral administration is
not possible, the sublingual route may be used. Place 1
tablet under tongue for at least 5 minutes to allow for maximal absorption.
Patients should be advised not to swallow during disintegration time (Haegeli, 2007).
I.V. infusion solution mixed in NS
or D5W solution is stable for 24 hours at room
temperature. May also be diluted for infusion to 1-2 mg/mL
(maximum: 10 mg/mL).
Stable in D5LR, D5NS, D5W, D10W, D20W, mannitol 20%, LR, NS.
administration: Incompatible with amsacrine, azithromycin,
chlorpromazine, ciprofloxacin, diltiazem, droperidol, esmolol, fenoldopam, filgrastim, fluconazole, gemcitabine, gentamicin, hydralazine, idarubicin, labetalol, levofloxacin, metoclopramide, midazolam, milrinone, nesiritide, nicardipine, ondansetron, phenylephrine, quinidine gluconate, vasopressin,
vecuronium, vinblastine, vincristine, vinorelbine.
in syringe: Incompatible with
caffeine citrate, dimenhydrinate, doxapram,
doxorubicin, droperidol, metoclopramide,
milrinone, pantoprazole, vinblastine, vincristine.
when admixed: Incompatible with buprenorphine, chlorpromazine,
diazepam, dobutamine, erythromycin lactobionate, isoproterenol, meperidine, metoclopramide, prochlorperazine edisylate, promethazine.
Store at room temperature of 15°C to 30°C (59°F to 86°F). Protect from light. Exposure
to light may cause discoloration; do not use furosemide
solutions if they have a yellow color. Furosemide
solutions are unstable in acidic media, but very stable in basic media.
Refrigeration may result in precipitation or crystallization; however, resolubilization at room temperature or warming may be
performed without affecting the drug's stability.
Store at 25°C (77°F); excursions permitted to 15°C to 30°C (59°F to 89°F).
Protect from light.
Monitoring and Teaching Issues
Assess for allergy to
sulfonylurea before beginning therapy. Assess potential for interactions with
other pharmacological agents or herbal products patient may be taking
(especially anything that may impact fluid balance, electrolyte balance, or increase
potential for ototoxicity or hypotension). For
intravenous use, see Administration specifics. Assess results of laboratory
tests (electrolytes), therapeutic effectiveness, and adverse response on a
regular basis during therapy (eg, dehydration,
electrolyte imbalance, postural hypotension). Caution patients with diabetes
about closely monitoring glucose levels (glucose tolerance may be decreased).
Teach patient appropriate use, possible side effects/appropriate interventions,
and adverse symptoms to report.
Patient Education: Do not take any new medication during
therapy unless approved by prescriber. Take as directed with food or milk (to
reduce GI distress) early in the day (daily), or if twice daily, take last dose
in late afternoon in order to avoid sleep disturbance and achieve maximum
therapeutic effect. Keep medication in original container, away from light; do
not use discolored medication. Follow dietary advice of prescriber; include
bananas or orange juice or other potassium-rich foods in daily diet. Do not
take potassium supplements without advice of prescriber. If you have diabetes,
monitor glucose levels closely (this medication may alter glucose tolerance
requiring an adjustment in the dose of hypoglycemic agent). Weigh yourself each
day, at the same time, in the same clothes when beginning therapy and weekly on
longterm therapy. Report unusual or
unanticipated weight gain or loss. May cause dizziness, blurred vision,
or drowsiness (use caution when driving or engaging in tasks that require alertness
until response to drug is known); postural hypotension (use caution when rising
from lying or sitting position or when climbing stairs); or sensitivity to
sunlight (use sunblock or wear protective clothing
and sunglasses). Report signs of edema (eg, weight
gains; swollen ankles, feet, or hands), trembling, numbness or fatigue,
cramping or muscle weakness, palpitations, unresolved nausea or vomiting, or change
in hearing. Pregnancy/breast-feeding
prescriber if you are or intend to become pregnant. Consult prescriber if
May cause potassium
loss; potassium supplement or dietary changes may be required.
Loop diuretics are potent diuretics; excess
amounts can lead to profound diuresis with fluid and
electrolyte loss; close medical supervision and dose evaluation is required,
particularly in the elderly. Severe loss of sodium and/or increase in BUN can
cause confusion. For any change in mental status in patients on furosemide, monitor electrolytes and renal function.
Crosses into breast
milk; may suppress lactation. AAP has NO RECOMMENDATION.
Pregnancy Issues: Animal studies have demonstrated maternal
death, fetal toxicity, and fetal loss. There are no adequate and
well-controlled studies in pregnant women. Crosses the placenta.
Increased fetal urine production, electrolyte disturbances reported. Generally,
use of diuretics during pregnancy is avoided due to risk of decreased placental