Loop diuretics

Question 1

Indication
Loop diuretic

Answer 1

Oedema associated with heart failure, hepatic cirrhosis, renal impairment and nephrotic syndrome

Question 2

MOA
Loop diuretic

Answer 2

Inhibit reabsorption of sodium and chloride in the ascending limb of the loop of Henle. This site accounts for retention of approximately 20% of filtered sodium; therefore, these are potent diuretics.

Produce a rapid and intense diuresis and have a short duration of action (4–6 hours). They are effective over a wide dose range with a dose-related response.

Question 3

Precautions
Loop Diuretics

Answer 3

Allergy to the specific loop diuretic—contraindicated (see Comparative information below).

Prostatic obstruction—loop diuretics may precipitate acute urinary retention.

Gout—may be aggravated by diuretic-induced hyperuricaemia. If a regular loop diuretic is started after the target serum urate level has been reached, measure serum urate levels every 2–5 weeks and adjust dose of urate-lowering drugs if necessary.

Treatment with ototoxic drugs—increases risk of ototoxicity with loop diuretics; use combinations carefully, especially in renal impairment.

Question 4

Adverse effects
Loop diuretics

Answer 4

electrolyte disturbances (eg hyponatraemia, hypokalaemia, hypomagnesaemia, hypochloraemia, hypocalcaemia), dehydration, metabolic alkalosis, increased creatinine concentration, hyperuricaemia, gout, dizziness, orthostatic hypotension, fainting

Question 5

Nursing considerations
Loop diuretic

Answer 5

Furosemide is the only loop diuretic available in oral and IV formulations.

Bumetanide may be used in patients allergic to furosemide (eg rash) but risk of cross-reactivity cannot be excluded.

Can cause hypotension which can cause dizziness

in case of heart failure:
1. Start with low dose
2. combine with ACE inhibitor

This medicine is usually taken once daily in the morning. If you are taking it twice a day, take the first dose in the morning and the second dose at lunchtime.

You may feel dizzy on standing when taking this medicine. Get up gradually from sitting or lying to minimise this effect; sit or lie down if you become dizzy.
role of loop diuretics in hypertension is limited to management of excess salt and water retention inadequately controlled by other antihypertensive treatment

**Heart failure
**start with a low dose then adjust according to clinical response; use the lowest effective maintenance dose
combine with an ACE inhibitor
if hypotension occurs decrease dose of diuretic before that of the ACE inhibitor
usually given once daily in the morning although there may be a better clinical response if the drug is given twice daily (second dose is usually given at midday; diuresis may interfere with sleep if given after 6 pm)
higher doses are necessary in refractory heart failure:
a trial of IV furosemide may be more effective than increasing oral doses
increase diuretic effect by adding a thiazide diuretic; use small, intermittent thiazide doses with careful monitoring, seek specialist advice
monitor weight and electrolytes
hypokalaemia is less likely when diuretics are used with ACE inhibitors or sartans than when used alone

Question 6

Drug class and indication

Bumetanide

Answer 6

Loop diuretic
Oedema associated with heart failure, hepatic cirrhosis, renal impairment and nephrotic syndrome

Given if furosemide is not tolerated

Question 7

Drug class and indication

Furosemide

Answer 7

Loop diuretic
Oedema associated with heart failure, hepatic cirrhosis, renal impairment and nephrotic syndrome