Furosemide

Introduction: Furosemide belongs to a group of medicines called diuretics or water tablets. It is used to reduce the swelling (edema) caused by too much water in the body in people who have heart failure, liver or kidney disease. This medicine is also used to treat high blood pressure.

How it works: Furosemide inhibits reabsorption of sodium and chloride mainly in the medullary portion of the ascending Loop of Henle. It helps your body get rid of extra water and salt through urine.

Important Information: It can be taken with or without food and should be taken at the same time each day. Avoid taking this medicine within 4 hours of bedtime. Continue taking this medication even if you feel well.

• Fluid retention: associated with chronic congestive cardiac failure, acute congestive cardiac failure, chronic renal failure, nephrotic syndrome, and liver disease.
• Maintenance of fluid excretion in acute renal failure - including that due to pregnancy or burns.
• Hypertension
• Hypertensive crisis - as a supportive measure
• Support of forced diuresis

Loop diuretics

Monosulphonyl diuretic

Furosemide is a monosulphonyl diuretic. It is an effective diuretic that retains its activity even in low glomerular filtration rate (GFR). Furosemide has a distinctive action on renal tubular function. It inhibits sodium and chloride transport in the ascending limb of the loop of Henle and acts independently of acid-base balance changes.

Furosemide inhibits the Na+/K+/2Cl- co-transporter in the thick ascending limb of the loop of Henle, blocking reabsorption of sodium, potassium and chloride ions, thereby increasing the quantity of sodium and water excreted in the urine.

Adult Dose (Oral):

• Edema: Initial 40 mg daily, reduced to 20 mg daily or 40 mg on alternate days. Resistant edema: 80-120 mg daily. Severe cases: up to 600 mg/day.
• Hypertension: Initial 80 mg (usually 40 mg twice daily), adjust according to response.

Child Dose (Oral):

• Neonate: 0.5-2 mg/kg every 12-24 hours.
• 1 month-12 years: 0.5-2 mg/kg 2-3 times daily (max 12 mg/kg/day, not to exceed 80 mg/day).
• 12-18 years: 20-40 mg daily, resistant edema 80-120 mg daily.

Parenteral Dose:

• Adult: Initial 20-50 mg IM/IV, increase by 20 mg (every 2 hours).

Elderly: Slower elimination - titrate dosage.

* Use as directed by the registered physician

Oral tablet/syrup or parenteral (IM/IV). Swallow whole, do not chew or crush. Take in the morning with breakfast (to avoid waking up at night).

If you miss a dose, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular schedule. Do not double the dose.

Common Side Effects:

• Dizziness
• Weakness
• Dehydration
• Decreased potassium level in blood
• Increased blood uric acid
• Decreased magnesium level in blood
• Increased thirst

With prolonged use: Electrolyte imbalance, alkalosis, hyperglycemia, glycosuria.

Precautions:

• Patients with prostatic hypertrophy or impairment of micturition have increased risk of acute retention.
• Marked fall in blood pressure may occur when ACE inhibitors are added.
• Toxic effects of nephrotoxic antibiotics may be increased.
• Driving or hazardous tasks - blood pressure reduction may impair concentration and reaction.

Contraindications:

• Anuria
• Electrolyte deficiency
• Pre-comatose states associated with liver cirrhosis
• Hypersensitivity to furosemide or sulphonamides
• Addison's disease

Drug Interactions:

• ACE inhibitors: Marked fall in blood pressure.
• Lithium: Serum lithium levels may be increased.
• Aminoglycosides: Increased risk of ototoxicity.
• NSAIDs: Reduce diuretic and antihypertensive effects.
• Cardiac glycosides: Increased incidence of premature beats.

Food Interactions:

• Unsafe to consume alcohol with Furosemide.

Use in Pregnancy: May be unsafe during pregnancy. Animal studies have shown harmful effects. Use with caution in cardiogenic shock.

Use in Lactation: Probably safe during breastfeeding. Limited data suggests the drug does not represent significant risk to the baby. Furosemide may inhibit lactation or pass into breast milk.

Pediatric Use: Dosage available from neonates to 18 years.

Geriatric Use: Furosemide is generally eliminated more slowly in the elderly - titrate dosage.

Renal Impairment: Safe in kidney disease (no dose adjustment needed), but avoid in severe kidney disease (anuria).

Hepatic Impairment: Use with caution in liver disease. Dose adjustment may be needed.

Overdose:

• Symptoms: Hypovolaemia, dehydration, haemoconcentration, cardiac arrhythmias (including AV block and ventricular fibrillation).
• Treatment: No specific antidote. Gastric lavage and activated charcoal.

Storage: Protect from light. Do not use after expiry date. Keep out of reach of children.

Furosemide Tablet/Injection