Indications
Frusemide & Spironolactone combination is indicated in-
- Essential hypertension
- Chronic congestive heart failure
- Hepatic cirrhosis, with collection of fluid in the abdominal cavity (ascites)
- Swelling due to excess fluid retention (edema)
- Hyperaldosteronism
- Resistant edema associated with secondary hyperaldosteronism
Pharmacology
Spironolactone (potassium sparing diuretic) and Furosemide (loop diuretic) have different but complementary mechanisms and sites of action. Therefore, when given together they produce additive or synergistic diuretic. The Furosemide component inhibits the Na+/K+/2Cl- co-transporter in the ascending Loop of Henle and blocks the reabsorption of sodium, potassium and chloride ions; thereby increasing the quantity of sodium and the volume of water excreted in the urine. This characteristically induces potassium loss. The spironolactone component inhibits the reabsorption of sodium in exchange for potassium at the distal tubule by antagonising the action of aldosterone so that sodium excretion is greatly favoured and the excess loss of potassium, induced by the Furosemide, is reduced
Interaction
When taken together with ACE inhibitors or potassium salts there is an increased risk of hyperkalemia. Spironolactone increases the levels of cardiac glycosides such as digoxin in the blood and this may result in digitalis toxicity. Corticosteroids may cause hypokalemia if they are used with Spironolactone. The blood pressure lowering and diuretic effects of Furosemide may be reduced or abolished when used together with indomethacin and possibly other non-steroidal anti-inflammatory drugs (NSAIDs). Furosemide may increase the ototoxicity of aminoglycoside antibiotics. Simultaneous administration of sucralfate and Furosemide may reduce the natriuretic and anti-hypertensive effect of Furosemide.
Contraindications
Contraindicated in patients with anuria, acute renal insufficiency, rapidly deteriorating or severe impairment of renal function (creatinine clearance <30 ml/min), hyperkalaemia, Addison’s disease and in patients who are hypersensitive to Spironolactone, Furosemide or sulphonamides.
Pregnancy & Lactation
Pregnancy: Spironolactone and its metabolites may cross the placental barrier. The use of spironolactone in pregnant women requires that the anticipated benefit be weighed against the possible hazards to the mother and fetus. Animal teratology studies indicate that Furosemide may cause fetal abnormalities. Therefore, Furosemide should only be used in women in child bearing age when appropriate contraceptive measures are taken or if the potential benefits justify the potential risks to the fetus.
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