Loop diuretics

Question 1

Which conditions are loop diuretics prescribed for

Answer 1

Used in pulmonary oedema due to LV failure and for management of oedema in patients with chronic HF

Question 2

MoA

Answer 2

Loop diuretics inhibit sodium and chloride reabsorption from the ascending limb of the loop of Henlé in the renal tubule and are powerful diuretics

Question 3

Discuss the use of loop diuretics in pulmonary oedema due to LV failure

Answer 3

• IV administration will produce relief of breathlessness
• It reduces pre-load sooner than would be expected from the time of onset of diuresis (increased/excessive urine production)
• Decreases preload helps reduce the amount of blood the heart has to pump

Question 4

What is diuretic resistant oedema

Answer 4

Failure to achieve the therapeutically desired reduction in oedema even when a maximal dose of diuretic is employed

Question 5

How to treat diuretic resistant oedema (except lymphoedema and oedema due to peripheral venous stasis or CCB)

Answer 5

Loop diuretic + thiazide or related diuretic (e.g. bendroflumethiazide or metolazone)

Question 6

Examples of loop diuretics

Answer 6

Furosemide
Torasemide
Bumetanide

Question 7

Using a loop diuretic in antihypertensive patients

Answer 7

Loop diuretic can be added to antihypertensive treatment to achieve better control of BP in pt with resistant hypertension or impaired renal function or HF

Question 8

Which conditions may loop diuretics exacerbate

Answer 8

Diabetes
Gout

Question 9

What is the advantage of using loop diuretics in pt with diabetes over thiazides?

Answer 9

Although loop diuretics can exacerbate diabetes, hyperglycaemia is less likely than with thiazides

Question 10

Using loop diuretics in pt with enlarges prostate

Answer 10

Urinary retention may occur, but is less likely if small doses and less potent diuretics are used initially
Manufacturer advises adequate urinary output should be established before initiating treatment

Question 11

Activity of furosemide and bumetanide

Answer 11

• Similar activity
• Diuresis is dose related
• Act within 1h or oral administration
• Diuresis complete within 6 hours - if necessary, can be given BD without interfering sleep
• Following IV administration, furosemide has peak effect within 30 mins

Question 12

Activity of torasemide

Answer 12

• Similar properties to furosemide and bumetanide
• Indicated for oedema and hypertension

Question 13

Pt parameters to check before starting loop diuretic

Answer 13

Renal function, serum electrolytes, BP

Question 14

Monitoring requirements after starting treatment

Answer 14

• Recheck renal function, serum electrolytes and BP 1-2 weeks after starting treatment
• Earlier monitoring (after 5-7 days) may be required in people with:
• existing CKD stage 3 or higher
• 60 or over
• relevant comorbidities e.g. DM, peripheral arterial disease
• taking diuretic + ACEi/ARB/MRA

Question 15

Recommended starting dose of bumetanide for people with HF

Answer 15

0.5mg in the elderly to 1mg

Question 16

Recommended starting dose of furosemide in pt with HF

Answer 16

20-40mg

Question 17

Recommended starting dose of torasemide in pt with HF

Answer 17

5-10mg

Question 18

Daily dose of bumetanide in pt with HF

Answer 18

1-5mg
Elderly 0.5mg

Question 19

Daily dose of furosemide in pt with HF

Answer 19

20-120mg

Question 20

Daily dose of torasemide in pt with HF

Answer 20

10-20mg

Question 21

Dose titration

Answer 21

• Start with low dose
• Titrate dose up or down according to symptoms and signs of fluid overload
• Use the lowest possible dose to control symptoms

Question 22

Excessive diuresis can cause…

Answer 22

• postural hypotension
• dehydration
• AKI
• electrolyte imbalances

Question 23

What to do if pt shows evidence of symptomatic hypotension, dizziness, light headedness or confusion

Answer 23

• Consider reducing dose of diuretic OR
• Reducing dose of any concomitant drug known to reduce BP , OR
• Seeking expert advice

Question 24

When is the dose of loop diuretic normally given?

Answer 24

• Usually once daily in the morning
• Can be given twice daily (morning & lunchtime) for additional diuresis
• Pt can be advised to adjust timing of doses to suit their social needs

Question 25

Max initial dose for people with HF and preserved ejection fraction

Answer 25

Max initial dose is up to 80mg furosemide

Question 26

You need to provide eduction to the pt/carer regarding... (3 points)

Answer 26

- how to adjust dose according to changes in weight - avoiding excessive fluid intake - avoiding dehydration (thirst, dizziness, fatigue)

Question 27

What to advice the patient if they develop diarrhoea and vomiting while taking diuretic

Answer 27

- maintain fluid intake and stop diuretic for 1-2 days until they recover - stopping treatment for a short time is thought to avoid dehydration, hypotension, and AKI, and should not cause a sudden deterioration in HF - if symptoms persist beyond 2 days see a GP and have bloods checked

Question 28

What to do after restoration of dry body weight (removal of most or all pt excess fluid) and subsequent treatment for HF has been introduced

Answer 28

- Review loop diuretic dose and adjust as necessary - This will reduce risk of dehydration, AKI and electrolyte disturbances

Question 29

Monitoring after each dose increase

Answer 29

- Renal function, serum electrolytes and BP 1-2 weeks after each dose - Earlier monitoring (after 5-7 days) may be required for pt with - existing CKD stage 3 or higher - 60 or over - relevant comorbidities such as DM or peripheral arterial disease - combination of diuretic + ACEi, ARB, MRA

Question 30

Monitoring requirements once treatment is stable

Answer 30

Renal function + serum electrolytes at least once every 6 months

Question 31

Contraindications for all loop diuretics

Answer 31

- Anuria - Comatose and pre comatose states associated with liver cirrhosis - Renal failure due to nephrotoxic or hepatotoxic drugs - Severe hypokalaemia - Severe hyponatraemia

Question 32

Cautions for all loop diuretics

Answer 32

- Can exacerbate diabetes (but hyperglycaemia less likely than with thiazides) - Can exacerbate gout - Correct hypotension before initiation - Correct hypovolaemia before initiation - Urinary retention may occur in prostatic hyperplasia - Elderly: lower initial doses may be necessary because they are particularly susceptible to SE, and adjust dose according to renal function

Question 33

Prescription potentially inappropriate STOPP criteria for elderly

Answer 33

- as 1st line treatment for hypertension - there is safer, more effective alternatives - for treatment of hypertension with concurrent urinary incontiennce - may exacerbate incontinence - for dependent ankle oedema without evidence of HF, liver failure, nephrotic syndrome or renal failure: leg elevation/compression hosiery usually more appropriate

Question 34

Potassium loss

Answer 34

- hypokalaemia may occur in loop diuretics - this is dangerous in severe CVD and in pt being treated with cardiac glycosides - often the use of potassium-sparing diuretics avoids the need to take potassium supplements - in hepatic impairment, hypokalaemia caused by diuretics can precipitate encephalopathy

Question 35

Common or very common SE for all loop diuretics

Answer 35

- dizziness - electrolyte imbalance - fatigue - headache - metabolic alkalosis - muscle spasms - nausea

Question 36

State an uncommon side effect of loop diuretics

Answer 36

diarrhoea

Question 37

Hepatic impairment

Answer 37

- hypokalaemia induced by loop diuretics may precipitate hepatic encephalopathy and coma - potassium sparing diuretics can be used to prevent this - diuretics can increase risk hypomagnesaemia in alcoholic cirrhosis leading to arrhythmias

Question 38

Renal impairment

Answer 38

- high doses or rapid IV administration can cause tinnitus and deafness - high doses may occasionally be needed in renal impairment

Question 39

Furosemide - use in pregnancy and BF

Answer 39

Preg: do not use to treat gestational hypertension because of maternal hypovolaemia associated with this condition BF: amount too small to be harmful, may inhibit lactation

Question 40

Bumetanide in pregnancy and BF

Answer 40

Preg: do not use to treat gestational hypertension because of the maternal hypovolaemia associated with this condition BF: no info available, may inhibit lactation

Question 41

Torasemide in pregnancy and BF

Answer 41

Preg: avoid BF: avoid

Question 42

The following 2 side effects are more common in RI

Answer 42

deafness tinnitus

Question 43

What electrolyte disturbances can they cause

Answer 43

hypoMg hypoK hypoNa

Question 44

The following drugs increase the risk of hypokalaemia = increased risk of TDP

Answer 44

antipsychotics, citalopram, clomipramine, erythromycin, dronedarone, fluconazole, quinines, hydroxyzine, methadone, ranolazine, sotalol,

Question 45

The following drugs increase the risk of hyponatraemia

Answer 45

Carb, SSRIs, antipsychotics, loop diuretics, NSAIDs, SNRIs, TCAs, diuretics, vinca alkaloids

Question 46

Interaction with lithium

Answer 46

Loops increases the concentration of Lithium. Manufacturer advises monitor and adjust dose.

Question 47

The following drugs increase the risk of ototoxicity

Answer 47

quinines, AGs, amph B, platins, vancomycin, vinca alkaloids

Question 48

Avoid this class of drugs due to increased risk of nephrotoxicity (+ another interaction)

Answer 48

AGs also ototoxicity