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Furosemide
Injection, USP
(10 mg/mL)
Fliptop Vial
Ansyr™ Plastic Syringe
Rx only
WARNING: Furosemide is a potent diuretic which, if given in excessive amounts, can lead to a profound diuresis with water and electrolyte depletion. Therefore, careful medical supervision is required and dose schedule must be adjusted to the individual patient’s needs (see DOSAGE AND ADMINISTRATION).
DESCRIPTION
Furosemide is a diuretic which is an anthranilic acid derivative. Chemically it is 4-chloro- N -furfuryl- sulfamoylanthranilic acid.
Furosemide is a white to slightly-yellow crystalline powder. It is practically insoluble in water, sparingly soluble in alcohol, freely soluble in dilute alkali solutions and insoluble in dilute acids. It has the following structural formula:
Molecular formula: C 12 H 11 CI N 2 O 5 S
Molecular weight: 330.
Furosemide Injection, USP is a sterile solution intended for intramuscular or intravenous administration. Each mL contains furosemide 10 mg and sodium chloride sufficient to render solution isotonic in water for injection. Contains sodium hydroxide and may contain hydrochloric acid for pH adjustment. pH 9.0 (8.0 to 9.3).
The plastic syringe is molded from a specially formulated polypropylene. Water permeates from inside the container at an extremely slow rate which will have an insignificant effect on solution concentration over the expected shelf life.
Solutions in contact with the plastic container may leach out certain chemical components from the plastic in very small amounts; however, biological testing was supportive of the safety of the syringe material.
Contains no preservative.
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CLINICAL PHARMACOLOGY
Investigations into the mode of action of furosemide have utilized micropuncture studies in rats, stop flow experiments in dogs and various clearance studies in both humans and experimental animals.
It has been demonstrated that furosemide inhibits primarily the reabsorption of sodium and chloride not only in the proximal and distal tubules but also in the loop of Henle. The high degree of efficacy is largely due to the unique site of action. The action on the distal tubule is independent of any inhibitory effect on carbonic anhydrase and aldosterone.
Recent evidence suggests that furosemide glucuronide is the only or at least the major biotransformation product of furosemide in man. Furosemide is extensively bound to plasma proteins, mainly to albumin. Plasma concentrations ranging from 1 to 400 mcg/mL are 91 to 99% bound in healthy individuals. The unbound fraction averages 2.3 to 4.1% at therapeutic concentrations.
The onset of diuresis following intravenous administration is within 5 minutes and somewhat later after intramuscular administration. The peak effect occurs within the first half hour. The duration of diuretic effect is approximately 2 hours.
In fasted normal men, the mean bioavailability of furosemide from furosemide tablets and furosemide solution is 64% and 60%, respectively, of that from an intravenous injection of the drug. Although furosemide is more rapidly absorbed from the oral solution (50 minutes) than from the tablet (87 minutes), peak plasma levels and area under the plasma concentration-time curves do not differ significantly. Peak plasma concentrations increase with increasing dose but times-to-peak do not differ among doses. The terminal half-life of furosemide is approximately 2 hours.
Significantly more furosemide is excreted in urine following the intravenous injection than after the tablet or oral solution. There are no significant differences between the two oral formulations in the amount of unchanged drug excreted in urine.
Geriatric Population
Furosemide binding to albumin may be reduced in elderly patients. Furosemide is predominantly excreted unchanged in the urine. The renal clearance of furosemide after intravenous administration in older healthy male subjects (60 to 70 years of age) is statistically significantly smaller than in younger healthy male subjects (20 to 35 years of age). The initial diuretic effect of furosemide in older subjects is decreased relative to younger subjects (see PRECAUTIONS, Geriatric Use ).
INDICATIONS AND USAGE
Parenteral therapy should be reserved for patients unable to take oral medication or for patients in emergency clinical situations.
Edema
Furosemide is indicated in adults and pediatric patients for the treatment of edema associated with congestive heart failure, cirrhosis of the liver and renal disease, including the nephrotic syndrome. Furosemide is particularly useful when an agent with greater diuretic potential is desired.
Furosemide is indicated as adjunctive therapy in acute pulmonary edema. The intravenous administration of furosemide is indicated when a rapid onset of diuresis is desired, e.g., in acute pulmonary edema.
If gastrointestinal absorption is impaired or oral medication is not practical for any reason, furosemide is indicated by the intravenous or intramuscular route. Parenteral use should be replaced with oral furosemide as soon as practical.
CONTRAINDICATIONS
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In patients at high risk for radiocontrast nephropathy, furosemide can lead to a higher incidence of deterioration in renal function after receiving radiocontrast compared to high-risk patients who received only intravenous hydration prior to receiving radiocontrast.
In patients with hypoproteinemia (e.g., associated with nephrotic syndrome) the effect of furosemide may be weakened and its ototoxicity potentiated.
Asymptomatic hyperuricemia can occur and gout may rarely be precipitated.
Patients allergic to sulfonamides may also be allergic to furosemide.
The possibility exists of exacerbation or activation of systemic lupus erythematosus.
As with many other drugs, patients should be observed regularly for the possible occurrence of blood dyscrasias, liver or kidney damage, or other idiosyncratic reactions.
Information for Patients
Patients receiving furosemide should be advised that they may experience symptoms from excessive fluid and/or electrolyte losses. The postural hypotension that sometimes occurs can usually be managed by getting up slowly. Potassium supplements and/or dietary measures may be needed to control or avoid hypokalemia.
Patients with diabetes mellitus should be told that furosemide may increase blood glucose levels and thereby affect urine glucose tests. The skin of some patients may be more sensitive to the effects of sunlight while taking furosemide.
Hypertensive patients should avoid medications that may increase blood pressure, including over-the-counter products for appetite suppression and cold symptoms.
Laboratory Tests
Serum electrolytes (particularly potassium), CO 2 , creatinine and BUN should be determined frequently during the first few months of furosemide therapy and periodically thereafter.
Serum and urine electrolyte determinations are particularly important when the patient is vomiting profusely or receiving parenteral fluids. Abnormalities should be corrected or the drug temporarily withdrawn. Other medications may also influence serum electrolytes.
Reversible elevations of BUN may occur and are associated with dehydration, which should be avoided, particularly in patients with renal insufficiency.
Urine and blood glucose should be checked periodically in diabetics receiving furosemide, even in those suspected of latent diabetes.
Furosemide may lower serum levels of calcium (rarely cases of tetany have been reported) and magnesium. Accordingly, serum levels of these electrolytes should be determined periodically.
In premature infants furosemide may precipitate nephrocalcinosis/nephrolithiasis, therefore renal function must be monitored and renal ultrasonography performed (see PRECAUTIONS , Pediatric Use ).
Drug Interactions
Furosemide may increase the ototoxic potential of aminoglycoside antibiotics, especially in the presence of impaired renal function. Except in life-threatening situations, avoid this combination.
Furosemide should not be used concomitantly with ethacrynic acid because of the possibility of ototoxicity. Patients receiving high doses of salicylates concomitantly with furosemide, as in rheumatic disease, may experience salicylate toxicity at lower doses because of competitive renal excretory sites.
There is a risk of ototoxic effects if cisplatin and furosemide are given concomitantly. In addition, nephrotoxicity of nephrotoxic drugs such as cisplatin may be enhanced if furosemide is not given in lower doses and with positive fluid balance when used to achieve forced diuresis during cisplatin treatment.
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Furosemide has a tendency to antagonize the skeletal muscle relaxing effect of tubocurarine and may potentiate the action of succinylcholine.
Lithium generally should not be given with diuretics because they reduce lithium’s renal clearance and add a high risk of lithium toxicity.
Furosemide combined with angiotensin converting enzyme inhibitors or angiotensin II receptor blockers may lead to severe hypotension and deterioration in renal function, including renal failure. An interruption or reduction in the dosage of furosemide, angiotensin converting enzyme inhibitors, or angiotensin receptor blockers may be necessary.
Potentiation occurs with ganglionic or peripheral adrenergic blocking drugs.
Furosemide may decrease arterial responsiveness to norepinephrine. However, norepinephrine may still be used effectively.
Simultaneous administration of sucralfate and Furosemide Injection may reduce the natriuretic and antihypertensive effects of furosemide. Patients receiving both drugs should be observed closely to determine if the desired diuretic and/or antihypertensive effect of furosemide is achieved. The intake of furosemide and sucralfate should be separated by at least 2 hours.
In isolated cases, intravenous administration of furosemide within 24 hours of taking chloral hydrate may lead to flushing, sweating attacks, restlessness, nausea, increase in blood pressure, and tachycardia. Use of furosemide concomitantly with chloral hydrate is therefore not recommended.
Phenytoin interferes directly with renal action of furosemide. There is evidence that treatment with phenytoin leads to decrease intestinal absorption of furosemide, and consequently to lower peak serum furosemide concentrations.
Methotrexate and other drugs that, like furosemide, undergo significant renal tubular secretion may reduce the effect of furosemide. Conversely, furosemide may decrease renal elimination of other drugs that undergo tubular secretion. High-dose treatment of both furosemide and these other drugs may result in elevated serum levels of these drugs and may potentiate their toxicity as well as the toxicity of furosemide.
Furosemide can increase the risk of cephalosporin-induced nephrotoxicity even in the setting of minor or transient renal impairment.
Concomitant use of cyclosporine and furosemide is associated with increased risk of gouty arthritis secondary to furosemide-induced hyperurecemia and cyclosporine impairment of renal urate excretion.
High doses (> 80 mg) of furosemide may inhibit the binding of thyroid hormones to carrier proteins and result in transient increase in free thyroid hormones, followed by an overall decrease in total thyroid hormone levels.
One study in six subjects demonstrated that the combination of furosemide and acetylsalicylic acid temporarily reduced creatinine clearance in patients with chronic renal insufficiency. There are case reports of patients who developed increased BUN, serum creatinine and serum potassium levels, and weight gain when furosemide was used in conjunction with NSAIDs.
Literature reports indicate that coadministration of indomethacin may reduce the natriuretic and antihypertensive effects of furosemide in some patients by inhibiting prostaglandin synthesis. Indomethacin may also affect plasma renin levels, aldosterone excretion, and renin profile evaluation. Patients receiving both indomethacin and furosemide should be observed closely to determine if the desired diuretic and/or antihypertensive effect of furosemide is achieved.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Furosemide was tested for carcinogenicity by oral administration in one strain of mice and one strain of rats. A small but significantly increased incidence of mammary gland carcinomas occurred in female mice at a dose
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Geriatric Use
Controlled clinical studies of furosemide did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for the elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal or cardiac function, and of concomitant disease or other drug therapy.
This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection and it may be useful to monitor renal function (see PRECAUTIONS, General and DOSAGE AND ADMINISTRATION ).
ADVERSE REACTIONS
Adverse reactions are categorized below by organ system and listed by decreasing severity.
Gastrointestinal System Reactions
(1) Hepatic encephalopathy in patients with hepatocellular insufficiency (2) Pancreatitis (3) Jaundice (intrahepatic cholestatic jaundice) (4) Increased liver enzymes (5) Anorexia (6) Oral and gastric irritation (7) Cramping (8) Diarrhea (9) Constipation (10) Nausea (11) Vomiting
Systemic Hypersensitivity Reactions
(1) Severe anaphylactic or anaphylactoid reactions (e.g., with shock) (2) Systemic vasculitis (3) Interstitial nephritis (4) Necrotizing angiitis
Central Nervous System Reactions
(1) Tinnitus and hearing loss (2) Paresthesias (3) Vertigo (4) Dizziness (5) Headache (6) Blurred vision (7) Xanthopsia
Hematologic Reactions
(1) Aplastic anemia (2)Thrombocytopenia (3) Agranulocytosis (4) Hemolytic anemia (5) Leukopenia (6) Anemia (7) Eosinophilia.
Dermatologic-Hypersensitivity Reactions
(1) Toxic epidermal necrolysis (2) Stevens-Johnson Syndrome (3) Erythema multiforme (4) Drug rash with eosinophila and systemic symptoms (5) Acute generalized exanthematous pustulosis (6) Exfoliative dermatitis (7) Bullous pemphigoid ( 8) Purpura (9) Photosensitivity (10) Rash (11) Pruritus (12) Urticaria
Cardiovascular Reactions
(1) Orthostatic hypotension may occur and be aggravated by alcohol, barbiturates or narcotics (2) Increase in cholesterol and triglyceride serum levels
Other Reactions
(1) Hyperglycemia (2) Glycosuria (3) Hyperuricemia (4) Muscle spasm (5) Weakness (6) Restlessness (7) Urinary bladder spasm (8) Thrombophlebitis (9) Transient injection site pain following intramuscular injection (10) Fever.
Whenever adverse reactions are moderate or severe, furosemide dosage should be reduced or therapy withdrawn.
OVERDOSAGE
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The principal signs and symptoms of overdose with furosemide are dehydration, blood volume reduction, hypotension, electrolyte imbalance, hypokalemia and hypochloremic alkalosis, and are extensions of its diuretic action.
The acute toxicity of furosemide has been determined in mice, rats and dogs. In all three, the oral LD 50 exceeded 1,000 mg/kg body weight, while the intravenous LD 50 ranged from 300 to 680 mg/kg. The acute intragastric toxicity in neonatal rats is 7 to 10 times that of adult rats.
The concentration of furosemide in biological fluids associated with toxicity or death is not known.
Treatment of overdosage is supportive and consists of replacement of excessive fluid and electrolyte losses. Serum electrolytes, carbon dioxide level and blood pressure should be determined frequently. Adequate drainage must be assured in patients with urinary bladder outlet obstruction (such as prostatic hypertrophy).
Hemodialysis does not accelerate furosemide elimination.
DOSAGE AND ADMINISTRATION
Adults
Parenteral therapy with Furosemide Injection, USP should be used only in patients unable to take oral medication or in emergency situations and should be replaced with oral therapy as soon as practical.
Edema The usual initial dose of furosemide is 20 to 40 mg given as a single dose, injected intramuscularly or intravenously. The intravenous dose should be given slowly (1 to 2 minutes). Ordinarily a prompt diuresis ensues. If needed, another dose may be administered in the same manner 2 hours later or the dose may be increased. The dose may be raised by 20 mg and given not sooner than 2 hours after the previous dose until the desired diuretic effect has been obtained. This individually determined single dose should then be given once or twice daily.
Therapy should be individualized according to patient response to gain maximal therapeutic response and to determine the minimal dose needed to maintain that response. Close medical supervision is necessary.
When furosemide is given for prolonged periods, careful clinical observation and laboratory monitoring are particularly advisable. (See PRECAUTIONS: Laboratory Tests .)
If the physician elects to use high dose parenteral therapy, add the furosemide to either Sodium Chloride Injection, USP, Lactated Ringer’s Injection, USP, or Dextrose Injection 5%, USP, after pH has been adjusted to above 5.5, and administer as a controlled intravenous infusion at a rate not greater than 4 mg/min. Furosemide Injection is a buffered alkaline solution with a pH of about 9 and the drug may precipitate at pH values below 7. Care must be taken to ensure that the pH of the prepared infusion solution is in the weakly alkaline to neutral range. Acid solutions, including other parenteral medications (e.g., labetalol, ciprofloxacin, amrinone, milrinone) must not be administered concurrently in the same infusion because they may cause precipitation of the furosemide. In addition, furosemide injection should not be added to a running intravenous line containing any of these acidic products.
Acute Pulmonary Edema- The usual initial dose of furosemide is 40 mg injected slowly intravenously (over 1 to 2 minutes). If a satisfactory response does not occur within 1 hour, the dose may be increased to 80 mg injected slowly intravenously (over 1 to 2 minutes).
If necessary, additional therapy (e.g., digitalis, oxygen) may be administered concomitantly.
Geriatric patients
In general, dose selection for the elderly patient should be cautious, usually starting at the low end of the dosing range (see PRECAUTIONS, Geriatric Use ).
Pediatric Patients
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Unit of Sale Concentration Each NDC 0409- 6102 - 02 Carton Containing 25 Vials
20 mg/2 mL (10 mg/mL)
NDC 0409-6102-
2 mL Single-use Vial NDC 0409- 6102 - 04 Carton Containing 25 Vials
40 mg/4 mL (10 mg/mL)
NDC 0409-6102-
4 mL Single-use Vial NDC 0409- 6102 - 10 Carton Containing 25 Vials
100 mg/10 mL (10 mg/mL)
NDC 0409-6102-
10 mL Single-use Vial NDC 0409- 1639 - 10 Bundle Containing 10 ANSYR Syringes
100 mg/10 mL (10 mg/mL)
NDC 0409-1639-
10 mL Single-use ANSYR Syringe NDC 0409- 9631 - 04 Bundle Containing 10 ANSYR Syringes
40 mg/4 mL (10 mg/mL)
NDC 0409-9631-
4 mL Single-use ANSYR Syringe
Store at 20 to 25°C (68 to 77°F). [See USP Controlled Room Temperature.]
Do not use if solution is discolored or contains particulate.
Protect from light. Do not remove the Ansyr syringe from carton until ready to use.
Discard unused portion.
Revised:
EN-
Hospira, Inc., Lake Forest, IL 60045 USA
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