Loop diuretics

Question 1

What are the generic and brand names of loop diuretics?

Answer 1

• Furosemide (Frumil)

* Bumetinide

Question 2

What is the method of action of loop diuretics?

Answer 2

• Acts mainly on ascending limb of the loop of Henle
• Inhibits Na+/K+/2Cl- co transporter
• This means electrolytes do not go into the epithelial cells and water does not follow
• Dilates veins = reduces preload and strain on heart
(see image in notes)

Question 3

What are the indications for loop diuretics?

Answer 3

• Acute pulmonary oedema – relieves breathlessness
• Fluid overload in chronic heart failure
• Fluid overload in other oedematous states e.g. renal/liver disease

Question 4

What are the contraindications of loop diuretics?

Answer 4

• Hypovolemia/dehydration
• Hypokalaemia/hyponatraemia
• Gout

Question 5

What are the side effects of loop diuretics?

Answer 5

• Dehydration
• Hypotension
• Electrolyte imbalance (low)
• Hearing loss/tinnitus – due to blocking cotransporter involved in regulating endolymph composition

Question 6

What are the interactions with loop diuretics?

Answer 6

• Affects drugs that are excreted by the kidneys e.g. lithium levels increase
• Digoxin = toxicity due to hypokalaemia
• Aminoglycosides = increases ototoxicity and nephrotoxicity

Question 7

What is the method of elimination of loop diuretics?

Answer 7

• Kidney

Question 8

What information should you give to a patient on a loop diuretic?

Answer 8

• Frequency of urination will increase

* Avoid doses late in the day as it may affect you at night