CARDIO + RENAL: LOOP DIURETICS

Question 1

LOOP DIURETICS: INDICATIONS

Answer 1

• For relief of breathlessness in acute pulmonary oedema in conjunction with oxygen and nitrates
• For symptomatic treatment of fluid overload in chronic heart failure
• For symptomatic treatment of fluid overload in other oedematous states, e.g. due to renal disease or liver failure, where they may be given in combination with other diuretics.

Question 2

LOOP DIURETICS: MOA

Answer 2

• Act on the ascending limb of the loop of Henle, where they inhibit the Na+/K+/2Cl−cotransporter.
• This protein transports sodium, potassium and chloride ions from the tubular lumen into the epithelial cell
• Water then follows by osmosis. Inhibiting this process has a potent diuretic effect
• In addition, loop diuretics have a direct effect on blood vessels, causing dilatation of capacitance veins. In acute heart failure, this reduces preload and improves contractile function of the ‘overstretched’ heart muscle.

Question 3

LOOP DIURETICS: ADVERSE EFFECTS

Answer 3

• Dehydration
• Hypotension
• Any low electrolyte state
• Hearing Loss
• Tinnitus

Question 4

LOOP DIURETICS: WARNINGS

Answer 4

• Hypovolemia
• Dehydration
• Hepatic Encephalopathy
• Hypokalaemia
• Hyponatraemia
• Can worsen gout

Question 5

LOOP DIURETICS: INTERACTIONS

Answer 5

• Drugs that are excreted by the kidneys
• For example, lithium levels are increased due to reduced excretion.
• The risk of digoxin toxicity may also be increased, due to the effects of diuretic-associated hypokalaemia
• Loop diuretics can increase the ototoxicity and nephrotoxicity of aminoglycosides

Question 6

LOOP DIURETICS: EXAMPLES

Answer 6

• Furosemide

- Bumetanide