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# Furosemide (Oral)
## Overview
Furosemide is a potent loop diuretic used for the management of edema associated with heart failure, liver cirrhosis, and renal disease, including the nephrotic syndrome. It is also used to treat hypertension, usually in combination with other antihypertensive agents.
## Primary Indications
* Edema due to heart failure, liver cirrhosis, and renal disease.
* Hypertension.
## Adult Dosing
* **Edema:** The typical starting dose is 20 mg to 80 mg orally once daily. The dose may be adjusted based on response, with subsequent doses given 6-8 hours later if needed. The usual maintenance dose is 40 mg to 120 mg per day, but doses up to 600 mg per day have been used in severe cases.
* **Hypertension:** The typical starting dose is 40 mg orally twice daily. It is usually used in combination with other antihypertensives.
## Pediatric Dosing
* **Edema:** 1 mg/kg to 2 mg/kg orally once daily, up to a maximum of 40 mg per day. Doses can be repeated every 6-8 hours as needed. For chronic use, the dose should be titrated to the lowest effective level.
## Dose Adjustments
* **Renal Impairment:** In patients with severe renal impairment, diuretic response may be reduced, and higher doses may be required. However, caution is advised as accumulation can occur.
* **Hepatic Impairment:** Dose adjustment may be necessary due to altered pharmacokinetics.
## Contraindications
* Anuria.
* Known hypersensitivity to furosemide or its sulfonamide moiety.
## Adverse Effects
* **Electrolyte imbalances:** Hypokalemia, hyponatremia, hypochloremia, hypomagnesemia, hypocalcemia.
* **Dehydration and hypovolemia.**
* **Ototoxicity:** Tinnitus, hearing impairment (often reversible, but can be permanent with high doses or rapid IV administration).
* **Hypotension.**
* **Hyperglycemia.**
* **Hyperuricemia:** Can precipitate gout.
* **Dizziness, lightheadedness.**
* **Rash, photosensitivity.**
## Key Drug Interactions
* **Aminoglycosides:** Increased risk of ototoxicity and nephrotoxicity.
* **Other ototoxic drugs:** Additive risk of ototoxicity.
* **Corticosteroids (systemic):** Increased risk of hypokalemia.
* **Digoxin:** Increased risk of digoxin toxicity due to furosemide-induced hypokalemia.
* **NSAIDs:** May reduce the diuretic and antihypertensive effects of furosemide and increase the risk of nephrotoxicity.
* **Lithium:** Furosemide can decrease lithium clearance, leading to increased serum lithium levels and potential toxicity.
* **Antihypertensives:** Additive hypotensive effects.
## Monitoring
* Electrolytes (sodium, potassium, chloride, magnesium, calcium)
* Renal function (BUN, creatinine)
* Blood pressure
* Urine output
* Hearing (especially with high doses or prolonged therapy)
* Blood glucose (in diabetic patients)
* Uric acid levels (in patients prone to gout)
## Clinical Pearls
* Administer oral furosemide with food or milk to minimize gastrointestinal upset.
* Dosing frequency and timing should be individualized to achieve optimal diuresis while minimizing nocturia.
* Closely monitor for signs and symptoms of electrolyte imbalance and dehydration.
* Correct hypokalemia before initiating or during therapy with drugs that prolong the QT interval.
* In patients with significant edema, weight loss of more than 1.5-2 kg per day may indicate excessive diuresis.
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*This information is intended for clinical use and does not replace the official prescribing information. Always consult the most current drug product labeling and relevant clinical guidelines before making any treatment decisions.*
