Generic Name: Furosemide.

Trade Name    : lasix.

Drug Class      : Loop Diuretics.

Forms of The Drug

  1. Injectable Solution (IV, IM; Generic): 10mg/mL.
  2. Injectable Solution (SC; Furoscix): 80mg/10mL Single-dose Prefilled Cartridge for on-Body Infusor.
  3. Oral Solution: 10mg/mL – 8mg/mL.
  4. Tablet: 20mg –  40mg – 80mg.

Mechanism of Action

Furosemide acts on the ascending limb of the loop of Henle in the kidneys, which is responsible for reabsorbing sodium, chloride, and water from the filtrate. It inhibits the reabsorption of sodium and chloride ions by blocking the Na-K-2Cl cotransporter in the luminal membrane of the renal tubular cells. This cotransporter is responsible for transporting sodium, potassium, and chloride ions into the cells from the tubular fluid. By inhibiting this cotransporter, furosemide prevents the reabsorption of sodium and chloride ions, leading to an increased concentration of these ions in the tubular fluid. This high concentration creates an osmotic gradient that promotes the retention of water in the tubular lumen, inhibiting its reabsorption. Consequently, more water and electrolytes are excreted in the urine, resulting in increased urine output (diuresis).

In addition to its effects on sodium, chloride, and water reabsorption, furosemide also has vasodilatory properties. It causes relaxation and dilation of the blood vessels, particularly the arteries, which reduces peripheral vascular resistance and decreases blood pressure. This vasodilation is believed to be due to the direct effect of furosemide on vascular smooth muscle cells. Furthermore, furosemide affects the reabsorption of other electrolytes in the renal tubules. It can cause increased excretion of potassium, calcium, and magnesium, which may lead to electrolyte imbalances if not monitored and managed appropriately.

Indications

  1. Edema.
  2. Congestive heart failure (CHF).
  3. Hypertension.
  4. Renal impairment.
  5. Hypercalcemia.
  6. Pulmonary edema.

Contraindications

  1. Allergy or hypersensitivity.
  2. Anuria.
  3. Severe electrolyte imbalances.
  4. Hepatic coma.
  5. Anencephaly.
  6. Severe dehydration.
  7. Pre-renal azotemia.
  8. Pregnancy and breastfeeding.

Side Effects

  1. Hyperuricemia (40%).
  2. Hypokalemia (14-60%).
  3. Dehydration.
  4. Low blood pressure.
  5. Ototoxicity.
  6. Gastrointestinal side effects such as nausea, vomiting, stomach cramps, diarrhea, or constipation.
  7. Hypersensitivity reactions.

Drug Interaction

Other drugs that can interact with it.

  1. Other diuretics such as thiazides or potassium-sparing diuretics.
  2. Aminoglycoside antibiotics e.g., gentamicin, tobramycin.
  3. Lithium.
  4. NSAIDs including ibuprofen and naproxen.
  5. Corticosteroids such as prednisone or dexamethasone.
  6. Digoxin.
  7. Antihypertensive medications such as beta-blockers or ACE inhibitors.
  8. Ototoxic medications such as cisplatin or certain antibiotics.

Precautions

  1. Pregnancy: Category C.
  2. Lactation: Furosemide, also known as Lasix, can be excreted into breast milk. Therefore, it is generally recommended to exercise caution when considering the use of furosemide during lactation.

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