ND Clinical Board Review: Furosemide

Today's med: Furosemide (fyoor OH se mide) (brand name: Lasix )

Drug Class: Diuretic, Loop

Other Drugs in this class: Bumetanide,Chlortalidone, Indapamide, Etacrynic acid,Caffeine, Triamterene, Pamabrom,Tolvaptan, Methyclothiazide,Hydroflumethiazide,Fosinopril/hydrochlorothiazide, Torsemide

Actions: 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

Indications: Management of edema associated with heart failure and hepatic or renal disease; acute pulmonary edema; treatment of hypertension (alone or in combination with other antihypertensives). Canadian labeling: Additional use: Furosemide Special Injection and Lasix® Special (products not available in the U.S.): Adjunctive treatment of oliguria in patients with severe renal impairment

Contraindications: Hypersensitivity to furosemide or any component of the formulation; anuria.

Adverse Effects: Cardiovascular: Acute hypotension, chronic aortitis, necrotizing angiitis, orthostatic hypotension, vasculitis; Central nervous system: Dizziness, fever, headache, hepatic encephalopathy, lightheadedness, restlessness, vertigo; Dermatologic: Bullous pemphigoid, cutaneous vasculitis, drug rash with eosinophilia and systemic symptoms (DRESS), erythema multiforme, exanthematous pustulosis (generalized), exfoliative dermatitis, photosensitivity, pruritus, purpura, rash, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria; Endocrine & metabolic: Cholesterol and triglycerides increased, glucose tolerance test altered, gout, hyperglycemia, hyperuricemia, hypocalcemia, hypochloremia, hypokalemia, hypomagnesemia, hyponatremia, metabolic alkalosis; Gastrointestinal: Anorexia, constipation, cramping, diarrhea, nausea, oral and gastric irritation, pancreatitis, vomiting; Genitourinary: Urinary bladder spasm, urinary frequency; Hematological: Agranulocytosis (rare), anemia, aplastic anemia (rare), eosinophilia, hemolytic anemia, leukopenia, thrombocytopenia; Hepatic: Intrahepatic cholestatic jaundice, ischemic hepatitis, liver enzymes increased

Local: Injection site pain (following I.M. injection), thrombophlebitis; Neuromuscular & skeletal:

Muscle spasm, paresthesia, weakness; Ocular: Blurred vision, xanthopsia;

Otic: Hearing impairment (reversible or permanent with rapid I.V. or I.M. administration), tinnitus;

Renal: Allergic interstitial nephritis, fall in glomerular filtration rate and renal blood flow

(due to overdiuresis),glycosuria, transient rise in BUN; Miscellaneous: Anaphylaxis (rare),

exacerbate or activate systemic lupus erythematosus.

Standard Dosing:
Infants and Children: Edema, heart failure:

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.M., 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

Children 1-17 years: Hypertension, resistant (unlabeled; AAP, 2004): Oral: Initial: 0.5-2 mg/kg/dose once or twice daily; maximum dose: 6 mg/kg/dose

Adults:

Edema, heart failure:

Oral: Initial: 20-80 mg/dose; if response is not adequate, may repeat the same dose or increase dose in increments of 20-40 mg/dose at intervals of 6-8 hours; may be titrated up to 600 mg/day with severe edematous states; usual maintenance dose interval is once or twice daily. Note: Dosing frequency may be adjusted based on patient-specific diuretic needs.

I.M., I.V.: Initial: 20-40 mg/dose; if response is 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.

Continuous 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.

Acute 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.

Hypertension, resistant (Chobanian, 2003; JNC 7): Oral: 20-80 mg/day in 2 divided doses

Refractory heart failure: Oral, I.V.: Doses up to 8 g/day have been used.

Elderly: Oral, I.M., I.V.: Initial: 20 mg/day; increase slowly to desired response.

Administration

I.V.: 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.

Oral: Administer on an empty stomach (Bard, 2004). May be administered with food or milk if GI distress occurs; however, this may reduce diuretic efficacy.

Note: 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).