What should you assess when taking furosemide?

Pharmacology & Drug Study (Notes)

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Drug Name

Generic Name :  furosemide

Brand Name: Apo-Furosemide (CAN), Furosemide Special (CAN), Lasix

Classification:  Loop diuretic

Pregnancy Category C

Dosage & Route

• Available forms :Tablets—20, 40, 80 mg; oral solution—10 mg/mL, 40 mg/5 mL; injection—10 mg/mL

ADULTS

• Edema: Initially, 20–80 mg/day PO as a single dose. If needed, a second dose may be given in 6–8 hr. If response is unsatisfactory, dose may be increased in 20- to 40-mg increments at 6- to 8-hr intervals. Up to 600 mg/day may be given. Intermittent dosage schedule (2–4 consecutive days/wk) is preferred for maintenance, or 20–40 mg IM or IV (slow IV injection over 1–2 min). May increase dose in increments of 20 mg in 2 hr. High-dose therapy should be given as infusion at rate not exceeding 4 mg/min.
• Acute pulmonary edema: 40 mg IV over 1–2 min. May be increased to 80 mg IV given over 1–2 min if response is unsatisfactory after 1 hr.
• Hypertension: 40 mg bid PO. If needed, additional antihypertensive agents may be added.

PEDIATRIC PATIENTS

Avoid use in premature infants: stimulates prostaglandin E2 synthesis and may increase incidence of patent ductus arteriosus and complicate respiratory distress syndrome.

• Edema: Initially, 2 mg/kg/day PO. If needed, increase by 1–2 mg/kg in 6–8 hr. Do not exceed 6 mg/kg. Adjust maintenance dose to lowest effective level.
• Pulmonary edema: 1 mg/kg IV or IM. May increase by 1 mg/kg in 2 hr until the desired effect is seen. Do not exceed 6 mg/kg.

PATIENTS WITH RENAL IMPAIRMENT

• Up to 4 g/day has been tolerated. IV bolus injection should not exceed 1 g/day given over 30 min.

Therapeutic actions

• Furosemide inhibits reabsorption of Na and chloride mainly in the medullary portion of the ascending Loop of Henle. Excretion of potassium and ammonia is also increased while uric acid excretion is reduced. It increases plasma-renin levels and secondary hyperaldosteronism may result. Furosemide reduces BP in hypertensives as well as in normotensives. It also reduces pulmonary oedema before diuresis has set in.

Indications

• Oral, IV: Edema associated with CHF, cirrhosis, renal disease
• IV: Acute pulmonary edema
• Oral: Hypertension

Adverse effects

• Fluid and electrolyte imbalance. Rashes, photosensitivity, nausea, diarrhoea, blurred vision, dizziness, headache, hypotension. Bone marrow depression (rare), hepatic dysfunction. Hyperglycaemia, glycosuria, ototoxicity.
• Potentially Fatal: Rarely, sudden death and cardiac arrest. Hypokalaemia and magnesium depletion can cause cardiac arrhythmias.

Contraindications

• Severe sodium and water depletion, hypersensitivity to sulphonamides and furosemide, hypokalaemia, hyponatraemia, precomatose states associated with liver cirrhosis, anuria or renal failure. Addison’s disease.

Nursing considerations

CLINICAL ALERT! Name confusion has occurred between furosemide and torsemide; use extreme caution.

Assessment

• History: Allergy to furosemide, sulfonamides, tartrazine; electrolyte depletion anuria, severe renal failure; hepatic coma; SLE; gout; diabetes mellitus; lactation, pregnancy
• Physical: Skin color, lesions, edema; orientation, reflexes, hearing; pulses, baseline ECG, BP, orthostatic BP, perfusion; R, pattern, adventitious sounds; liver evaluation, bowel sounds; urinary output patterns; CBC, serum electrolytes (including calcium), blood sugar, LFTs, renal function tests, uric acid, urinalysis, weight

Interventions

• BLACK BOX WARNING: Profound diuresis with water and electrolyte depletion can occur; careful medical supervision is required.
• Administer with food or milk to prevent GI upset.
• Reduce dosage if given with other antihypertensives; readjust dosage gradually as BP responds.
• Give early in the day so that increased urination will not disturb sleep.
• Avoid IV use if oral use is at all possible.
• WARNING: Do not mix parenteral solution with highly acidic solutions with pH below 3.5.
• Do not expose to light, may discolor tablets or solution; do not use discolored drug or solutions.
• Discard diluted solution after 24 hr.
• Refrigerate oral solution.
• Measure and record weight to monitor fluid changes.
• Arrange to monitor serum electrolytes, hydration, liver and renal function.
• Arrange for potassium-rich diet or supplemental potassium as needed.

Teaching points

• Record intermittent therapy on a calendar or dated envelopes. When possible, take the drug early so increased urination will not disturb sleep. Take with food or meals to prevent GI upset.
• Weigh yourself on a regular basis, at the same time and in the same clothing, and record the weight on your calendar.
• Blood glucose levels may become temporarily elevated in patients with diabetes after starting this drug.
• You may experience these side effects: Increased volume and frequency of urination; dizziness, feeling faint on arising, drowsiness (avoid rapid position changes; hazardous activities, like driving; and consumption of alcohol); sensitivity to sunlight (use sunglasses, wear protective clothing, or use a sunscreen); increased thirst (suck on sugarless lozenges; use frequent mouth care); loss of body potassium (a potassium-rich diet or potassium supplement will be needed).
• Report loss or gain of more than 3 pounds in 1 day, swelling in your ankles or fingers, unusual bleeding or bruising, dizziness, trembling, numbness, fatigue, muscle weakness or cramps.

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