furosemide

General

**BEERS Drug**

Pronunciation:
fur-oh-se-mide

Trade Name(s)

• Furoscix
• Lasix

Ther. Class.

diuretics

Pharm. Class.

loop diuretics

Indications

• PO IM IV Edema due to HF, hepatic impairment, or renal disease.
• SUBQ Edema due to chronic HF.
• PO Hypertension.

Action

• Inhibits the reabsorption of sodium and chloride from the loop of Henle and distal renal tubule.
• Increases renal excretion of water, sodium, chloride, magnesium, potassium, and calcium.
• Effectiveness persists in impaired renal function.

Therapeutic Effect(s):

• Diuresis and subsequent mobilization of excess fluid (edema, pleural effusions).
• Decreased BP.

Pharmacokinetics

Absorption: 60–67% absorbed after oral administration (↓ in acute HF and in renal failure); also absorbed from IM sites; IV administration results in complete availability; 99.6% absorbed after SUBQ administration.

Distribution: Unknown.

Protein Binding: 91–99%.

Metabolism and Excretion: Minimally metabolized by liver, some nonhepatic metabolism, some renal excretion as unchanged drug.

Half-life: 30–120 min (↑ in renal impairment).

TIME/ACTION PROFILE (diuretic effect)

Contraindication/Precautions

Contraindicated in:

• Hypersensitivity;
• Cross-sensitivity with thiazides and sulfonamides may occur;
• Hepatic coma;
• Anuria;
• Hepatic cirrhosis (SUBQ only);
• Alcohol intolerance (some liquid products may contain alcohol).

Use Cautiously in:

• Severe hepatic impairment (may precipitate hepatic coma; concurrent use with potassium-sparing diuretics may be necessary);
• Electrolyte depletion;
• Diabetes mellitus;
• Hypoproteinemia (↑ risk of ototoxicity);
• Severe renal impairment (↑ risk of ototoxicity);
• OB:   Use during pregnancy only if potential maternal benefit justifies potential fetal risk;
• Lactation:  Use while breastfeeding only if potential maternal benefit justifies potential risk to infant;
• Pedi:  ↑ risk for renal calculi and patent ductus arteriosis in premature neonates;
• Geri:  Appears on Beers list. May worsen or cause hyponatremia in older adults. Use with caution in older adults and monitor sodium concentrations closely when initiating therapy or ↑ the dose.

Adverse Reactions/Side Effects

CV: hypotension

Derm: ERYTHEMA MULTIFORME, photosensitivity, pruritus, rash, STEVENS-JOHNSON SYNDROME (SJS), TOXIC EPIDERMAL NECROLYSIS (TEN), urticaria

EENT: blurred vision, hearing loss, tinnitus

Endo: hyperglycemia

F and E: dehydration, hypocalcemia, hypochloremia, hypokalemia, hypomagnesemia, hyponatremia, hypovolemia, metabolic alkalosis

GI: ↑ liver enzymes, anorexia, constipation, diarrhea, dry mouth, dyspepsia, nausea, pancreatitis, vomiting

GU: excessive urination, nephrocalcinosis, renal impairment

Hemat: AGRANULOCYTOSIS, APLASTIC ANEMIA, hemolytic anemia, leukopenia, thrombocytopenia

Metabolic: hypercholesterolemia, hypertriglyceridemia, hyperuricemia

MS: muscle cramps

Neuro: dizziness, headache, paresthesia, vertigo

Misc: fever

* CAPITALS indicate life-threatening.
Underline indicate most frequent.

Interactions

Drug-Drug

• ↑ risk of hypotension with  antihypertensives,  nitrates, or acute ingestion of  alcohol.
• ↑ risk of hypokalemia with other  diuretics,  amphotericin B,  stimulant laxatives, and  corticosteroids.
• Hypokalemia may ↑ risk of  digoxin  toxicity and risk of arrhythmia in patients taking QT interval prolonging drugs.
• May ↑ risk of  lithium  toxicity.
• May ↑ risk of ototoxicity with  aminoglycosides  or  cisplatin.
• May ↑ risk of nephrotoxicity with  cisplatin.
•  NSAIDs  may ↓ effects of furosemide.
• May ↑ risk of  methotrexate  toxicity.
•  Sucralfate,  cholestyramine, or  colestipol  may ↓ absorption and effects.
• May ↑ risk of  salicylate  toxicity (with use of high-dose  salicylate  therapy).
• Concurrent use with  cyclosporine  may ↑ risk of gouty arthritis.

Route/Dosage

Edema

PO (Adults): 20–80 mg/day as a single dose initially; may repeat in 6–8 hr; may ↑ dose by 20–40 mg every 6–8 hr until desired response. Maintenance doses may be given once or twice daily (doses up to 2.5 g/day have been used in patients with HF or renal disease).  Hypertension:  40 mg twice daily initially (when added to regimen, ↓ dose of other antihypertensives by 50%); adjust further dosing based on response;  Hypercalcemia:  120 mg/day in 1–3 doses.

PO (Children >1 mo): 2 mg/kg as a single dose; may ↑ by 1–2 mg/kg every 6–8 hr (maximum dose = 6 mg/kg).

PO (Neonates): 1–4 mg/kg/dose 1–2 times/day.

IM IV (Adults): 20–40 mg; may repeat in 1–2 hr and ↑ by 20 mg every 1–2 hr until response is obtained; maintenance dose may be given every 6–12 hr;  Continuous infusion:  Bolus 0.1 mg/kg followed by 0.1 mg/kg/hr; double every 2 hr to a maximum of 0.4 mg/kg/hr.

IM IV (Children): 1–2 mg/kg/dose every 6–12 hr;  Continuous infusion:  0.05 mg/kg/hr; titrate to clinical effect.

IM IV (Neonates): 1–2 mg/kg/dose every 12–24 hr.

SUBQ (Adults): 30 mg over the 1st hr; then 12.5 mg per hr over the next 4 hr with the single-use on-body Infusor. Replace with oral diuretic therapy as soon as possible.

Hypertension

PO (Adults): 40 mg twice daily initially (when added to regimen, ↓ dose of other antihypertensives by 50%); adjust further dosing based on response.

Availability (generic available)

Tablets: 20 mg, 40 mg, 80 mg, 500 mg 

Oral solution (10 mg/mL–orange flavor, 8 mg/mL–pineapple-peach flavor): 8 mg/mL, 10 mg/mL

Solution for intravenous/intramuscular injection: 10 mg/mL

Solution for SUBQ injection (Furoscix) (prefilled cartridges): 80 mg/10 mL

Assessment

• Assess fluid status. Monitor daily weight, intake and output, amount and location of edema, lung sounds, skin turgor, and mucous membranes. Notify health care provider if thirst, dry mouth, lethargy, weakness, hypotension, or oliguria occurs.
• Monitor BP and HR before administration and throughout therapy.
• Assess for tinnitus and hearing loss. Audiometry is recommended for patients receiving prolonged high-dose IV therapy. Hearing loss is most common after rapid or high-dose IV administration in patients with renal impairment or those taking other ototoxic drugs.

Assess for rash frequently with signs and symptoms of SJS, TEN, or erythema multiforme during therapy (fever, general malaise, fatigue, muscle or joint aches, blisters, oral lesions, conjunctivitis, hepatitis, and/or eosinophila). Discontinue immediately and provide supportive care; may be life-threatening. May recur once treatment is stopped.

• Assess patients receiving digoxin for anorexia, nausea, vomiting, muscle cramps, paresthesia, and confusion; ↑ risk of digoxin toxicity because of the potassium-depleting effect of the diuretic. Potassium supplements or potassium-sparing diuretics may be used concurrently to prevent hypokalemia.
• Assess for tinnitus and hearing loss. Audiometry is recommended for patients receiving prolonged high-dose IV therapy. Hearing loss is most common after rapid or high-dose IV administration in patients with renal impairment or those taking other ototoxic drugs.

Geri:  Diuretic use is associated with ↑ risk for falls in older adults. Assess risk and implement fall prevention strategies.

• Assess for allergy to sulfonamides.

Lab Test Considerations:

Monitor electrolytes before and regularly during therapy. May ↓ sodium, potassium, calcium, and magnesium concentrations.

• Monitor renal and hepatic function, serum glucose, and uric acid levels before and periodically during therapy. May ↑ BUN, serum glucose, creatinine, and uric acid levels.

Implementation

• Do not confuse Lasix with Wakix.
• PO May be taken with food or milk to minimize GI irritation. Tablets may be crushed, if needed.
  • Do not administer discolored solution or tablets.

Black Box:  If given in excessive amounts, furosemide can lead to significant diuresis with water and electrolyte depletion. Careful medical supervision is required and dose regimen must be adjusted to the individual patient's needs.

• Administer medication in the morning to prevent disruption of sleep cycle. If administering twice daily, give last dose no later than 5 pm to minimize disruption of sleep cycle.

  • IV route is preferred over IM for parenteral administration.
• PO May be taken with food or milk to minimize GI irritation. Tablets may be crushed, if needed.
  • Do not administer discolored solution or tablets.

SUBQ The single-use on-body  infusor  with prefilled cartridge is preprogrammed to deliver 30 mg over 1st hr followed by 12.5 mg/hr for the subsequent 4 hr. Inspect fluid in prefilled cartridge; solution is clear to slightly yellow; do not administer if discolored or cloudy. Load prefilled cartridge and close. Peel adhesive liner on the  infusor  and apply to clean, dry skin of the abdomen between top of beltline and bottom of rib cage (>2½ inches from beltline or bottom of rib cage) that is not tender, bruised, red or indurated. Start injection by firmly pressing and releasing the start button. Do not remove until the injection is complete (signaled by the solid green status light, beeping sound, and white plunger rod filling the cartridge window). Rotate the site of each SUBQ administration. Patient must limit activity during administration. The  infusor  cannot be immersed fluids such as water, sweat, blood, etc. to prevent malfunction. Keep  infusor  >12 inches away from electronic devices or wireless accessories (TV remote, Bluetooth devices).  Infusor  must be removed prior to MRI. SUBQ route is not for chronic use; replace with oral diuretics as soon as practical.

Patient/Family Teaching

Explain purpose and side effects of furosemide. Instruct to take as directed. Take missed doses as soon as possible; do not double doses. Advise patient to read  Patient Information  before starting and with each Rx refill in case of changes.

• Emphasize the importance of routine follow-up examinations. Periodic lab tests will be needed.
•  Hypertension: Advise patients on antihypertensive regimen to continue taking medication even if feeling better. Furosemide controls but does not cure hypertension.
• Reinforce the need to continue additional therapies for hypertension (weight loss, exercise, restricted sodium intake, stress reduction, regular exercise, moderation of alcohol consumption, cessation of smoking).

• Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult health care professional before taking any OTC medications concurrently with this therapy.
• Caution patient to change positions slowly to minimize orthostatic hypotension. Caution patient that the use of alcohol, exercise during hot weather, or standing for long periods during therapy may enhance orthostatic hypotension.
• Instruct patient to consult health care professional regarding a diet high in potassium (see food sources for specific nutrients).
• Advise patient to contact health care professional if weight gain >3 lb in 1 day.
• Instruct patient to notify health care professional of medication regimen before treatment or surgery.
• Caution patient to use sunscreen and protective clothing to prevent photosensitivity reactions.
• Advise patient to contact health care professional immediately if rash, muscle weakness, cramps, nausea, dizziness, numbness, or tingling of extremities occurs.
• Advise patients with diabetes to monitor blood glucose closely; may cause ↑ blood glucose levels.
• Rep:  Advise women of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding. Loop diuretics are not recommended for use during pregnancy, except when necessary for treating pulmonary edema in cardiac failure. Monitor fetal growth during pregnancy; ↑ risk for higher birth weights.

• Geri:  Caution older patients or their caregivers about ↑ risk for falls. Suggest strategies for fall prevention.

• Rep:  Advise women of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding. Loop diuretics are not recommended for use during pregnancy, except when necessary for treating pulmonary edema in cardiac failure. Monitor fetal growth during pregnancy; ↑ risk for higher birth weights.

Evaluation/Desired Outcomes

• Diuresis and subsequent mobilization of excess fluid (edema, pleural effusions).
• Decrease in BP.