6.1 - Loop Diuretics

Front 1

Loop diuretics
1. drugs in class, brands (4 for frusemide), dose equivalence

Back 1

Frusemide = 40mg (Uremide, Urex, Frusid, Lasix)
Ethacrynic Acid = 50mg (Edecrin)
Bumetanide = 1mg (Burinex)

Front 2

Loop diuretics
2. MOA
3. Indications

Back 2

2. Acts on the loop of henle in the nephron to inhibit sodium and water retention. This site accounts for 20% of filtered sodium : therefore they are potent. A rapid and intense diuresis occurs lasting ~4-6hr. Dose related response.
3. Oedema associated with HF, LF, RF
*Also frusemide is used for hypercalcaemia (with hydration)

Front 3

Loop Diuretics
4. CIs (3)
5. Conditions worsened
6. LF/ RF
7. Preg/BF

Back 3

CI in
1. Severe sodium and fluid depletion
2. allergy to a specific loop diuretic
3. anuria
May worsen
(a) hypokalaemia (e.g. with amphotericin)
(b) BPH
(c) gout
(d) Nephro/oto-toxicity due to other drugs
6. LF - electrolyte imbalance may precipitate encephalopathy
RI - need high doses, monitor electrolytes, ototoxicity, RF
7. Preg Cat.C - avoid; may cause fetal electrolyte disturbance & blood disorders
BF: Caution - poss (but unlikely) suppression of lactation

Front 4

Loops
- A/Es

Back 4

common:
- lowers K, Na, fluid, Mg
- increases uric acid, gout
- dizziness, syncope, orthostatic hypotension

infrequent
- lowers ca
- dyslipidaemia
- rash

rare
- tinnitus, vertigo, deafness (esp with rapid IV)
- pancreatitis, jaundice, SJS, blood dyscrasias, nephritis

Front 5

Loops: Practice points
- Compare the loops

Back 5

Frusemide - only one available IV and oral

Bumetanide - used if frusemide allergy but there is a cross reactivity risk

Ethacrynic acid - used for allergy to both other loops but more A/Es: ototoxicity is more common (caution in RI); also can rarely cause GI toxicity (n/v/d/haemorrhage - cease), and hallucinations/mania

Front 6

Loops: Practice points
- when are high doses of loops used IV?
- when is it dosed

Back 6

- RF
- hyperCa
- in refractory HF, IV frusemide may be more effective than increasing oral doses
- m, or m + midi, give before 6pm if possible

Front 7

Ethacrynic acid
- brand
- dose form
- doses
- PBS?

Back 7

Edecrin
25mg.100 tabs
50-200mg d-bd
PBS-R[200]

Front 8

Bumetadine
- brand
- dose form
- doses
- PBS?

Back 8

Burinex
1mg.100
0.5-4mg d-bd

Front 9

Frusemide
- brands
- dose forms

Back 9

- Urex, Uremide, Lasix, Frusid
*20mg.50/100 (Frusid, Urex-M, Lasix-M)
*40mg.100 (Frusid, Lasix, Urex, Uremide etc)
*500mg.50 (Urex Forte)
*10mg/mL.30mL oral sol (Lasix)
*10mg/mL.2/4/8/25mL injections

Front 10

Frusemide
- oral BA
- oral doses
- children's doses
- hypercalcaemia doses

Back 10

- 50%
- start on 20-40mg d-bd; adjust; maintain on 20-400mg; max 1 g .
- 1-2mg/kg d-bd; max 6mg/kg
- 80-100mg IV q1-2h

Front 11

How should IV frusemide be administered?

Back 11

Slowly to avoid ototoxicity: no faster than 4mg/min

Front 12

Loops: Drug interactions?

Back 12

1. ototoxic and nephrotoxic drugs
2. hypotensive
3. hypokalaemia (e.g. amphotericin)
4. impaired RF - TZDs, ACEIs, NSAIDs (also concerned with electrolyte disturbances with thiazides; may need higher NSAID dose)
** Loops may increase Li concentrations: monitor