Drug Breakdown: Furosemide

Dr Sharon Rees @reesprescribe

Day 1: Discovered in the late 1950s, the loop diuretic #furosemide's chemical origins are traced back to sulfonamide derivatives. Despite not retaining the allergenic aromatic amine group, the product info still advises against taking if the patient has a history of sulfa-allergy.

Dr Sharon Rees @reesprescribe

Day 2: #furosemide remains in widespread use, mainly to manage oedema (pulmonary, heart failure and resistant oedema). Oral dose 40-120 mg/day (spans all indications), intramuscular (IM)/Intravenous (IV) titrated from 20-50 mg initially to max 1.5 g/day.

Dr Sharon Rees @reesprescribe

Day 2 (cont): IV diuresis starts within 10 minutes, oral within 1 hour, with a duration approximately 4-6 hrs. To preserve potassium (K+), can be combined with other diuretics (amiloride, triamterene, spironolactone) or K+.

Dr Sharon Rees @reesprescribe

Day 3: MOA; the Na-K-2Cl major transport proteins mediate salt absorption throughout nephron, especially in the loop of Henle. Competition from #furosemide inhibits reabsorption, causing increased water excretion (plus many electrolytes). Also vasodilatory action, enhancing treatment of acute pulmonary oedema.