Lasix Retard (Furosemide)

Furosemide is a loop diuretic used to manage fluid overload and high blood pressure in various clinical settings.

• Edema associated with heart failure: reduces excess fluid accumulation, improving symptoms such as shortness of breath and peripheral swelling.
• Edema associated with liver cirrhosis: promotes diuresis to alleviate ascites and peripheral edema.
• Edema associated with renal disease: enhances urinary output to manage fluid retention in chronic kidney conditions.
• Hypertension: lowers systemic vascular resistance and blood volume, contributing to blood pressure reduction.

• Furosemide acts on the thick ascending limb of the loop of Henle by inhibiting the Na⁺‑K⁺‑2Cl⁻ cotransporter. This blockade reduces reabsorption of sodium, chloride, and potassium, leading to increased excretion of these ions together with water. The resulting diuresis decreases extracellular fluid volume, helping to relieve edema and lower arterial pressure. The effect is rapid, typically beginning within 30 minutes after oral administration, and the magnitude of diuresis can be adjusted by dose.

Furosemide may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Electrolyte imbalance: low potassium, sodium or magnesium levels.
• Dehydration: excessive fluid loss leading to thirst and dizziness.
• Hypotension: drop in blood pressure, especially when standing.
• Increased urination: frequent or large volume urine output.
• Headache: mild to moderate headache episodes.
• Nausea: occasional stomach upset or vomiting.

Serious or Rare Side Effects

• Acute kidney injury: sudden decline in renal function.
• Ototoxicity: hearing loss or ringing in the ears, particularly with high doses.
• Severe allergic reaction: rash, itching, swelling, or anaphylaxis.
• Hyperuricemia: elevated uric acid causing gout attacks.
• Metabolic alkalosis: blood pH elevation due to loss of acid.
• Thrombocytopenia: low platelet count leading to bleeding risk.

When prescribing Furosemide, clinicians should consider several safety measures to minimize risks.

• Monitor electrolytes: check serum potassium, sodium and magnesium regularly.
• Assess renal function: evaluate creatinine and eGFR before and during therapy.
• Adjust dose in the elderly: start with lower doses due to increased sensitivity.
• Caution in diabetes: monitor blood glucose as diuresis may affect control.
• Avoid concurrent NSAIDs: they may reduce diuretic efficacy.
• Store at ambient temperature: keep below 25 °C in the original container, protect from moisture.

Furosemide can interact with other medicines, altering its effectiveness or increasing toxicity.

Major Interactions (Avoid)

• Aminoglycoside antibiotics: may increase risk of ototoxicity.
• Lithium: can cause lithium toxicity due to reduced renal clearance.
• High‑dose NSAIDs: may blunt diuretic response and worsen renal function.

Moderate Interactions (Monitor Closely)

• ACE inhibitors or ARBs: may enhance hypotensive effect and potassium loss.
• Antidiabetic agents: diuresis can affect glucose control.
• Corticosteroids: may potentiate fluid and electrolyte disturbances.