Furosémide

Furosémide, also known as furosemide, is a potent loop diuretic used to treat edema linked to heart failure, liver cirrhosis, and kidney disease, and to manage certain cases of hypertension. It is available in oral and parenteral forms and is widely used in hospital and outpatient settings.

Mechanism of action: Furosémide inhibits the Na+-K+-2Cl− cotransporter in the thick ascending limb of the loop of Henle. This action reduces reabsorption of sodium, chloride, and potassium, leading to increased excretion of water and electrolytes. The resulting diuresis lowers extracellular fluid volume and, over time, can reduce blood pressure.

Pharmacokinetics: Orally administered furosémide typically begins to work within 30 to 60 minutes, with peak effect in about 1–2 hours; the diuretic effect lasts roughly 4–6 hours. Intravenous administration produces a rapid effect within minutes; the duration is generally 2–4 hours. The drug is mainly excreted by the kidneys, and dose adjustments may be needed in kidney impairment.

Indications: Primary use is treatment of edema from congestive heart failure, nephrotic syndrome, or hepatic cirrhosis. It is also used for acute pulmonary edema and, in some situations, for resistant hypertension. It may be employed to promote calcium excretion in hypercalcemia following saline treatment.

Contraindications and precautions: Contraindicated in anuria and in hypersensitivity to furosémide or other sulfonamides. Caution is warranted in patients with dehydration, hypotension, electrolyte disturbances, gout, or pregnancy and lactation. Use with NSAIDs and other nephrotoxic agents may affect efficacy or safety.

Adverse effects and interactions: Common effects include dehydration and electrolyte disturbances (notably hypokalemia, hyponatremia, hypomagnesemia), as well as hyperuricemia and possible ototoxicity at high doses. Drug interactions include NSAIDs reducing effect, additive hypotension with other antihypertensives, and potential toxicity with digoxin or lithium in the context of electrolyte imbalance.