Diuretic dosing in edema

Loop diuretics

tip

Enteral equivalents: furosemide 40 mg = bumetanide 1 mg = ethacrynic acid 50 mg = torsemide 20 mg

Furosemide (Lasix®)

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Dose conversion: bioavailability is variable (10-100%); generally assume 2:1 potency for IV:enteral, but may want to be more cautious (1.5:1 or 1:1) depending on clinical scenario

Enteral

Onset of diuresis 30-60 min, with peak in 1-2 hours and duration of 6-8 hours
- Preemies: 1-2 mg/kg q12-24h
  - Max 2 mg/kg/day in ≤31 weeks adjusted (↑ risk of ototoxicity)
- Neonates: 1-2 mg/kg q6-8h
- Children: 1-2 mg/kg q6-24h
  - Max 6 mg/kg/dose (≤200 mg/dose, ≤10 mg/kg/day)
- Adults: 20-80 mg/dose q6-8h
  - Titrate by 20-40 mg q6-8h
  - Max 200 mg/dose (≤600 mg/day)

Intravenous (IV)

warning

To limit risk of ototoxicity, limit the infusion rate to a max of 0.5 mg/kg/min (4 mg/min) in children. In adults, limit infusion rate to 20-40 mg/minute for routine doses, but for high doses (≥160 mg) the rate should be limited to 4 mg/min.

Onset of diuresis ≤5 min, with peak in first 30 min and duration of ~2 hours
Intermittent
- Can also be given IM (dosed 1:1)
- Preemies: 0.5-1 mg/kg/dose q12-24h
  - Max 1 mg/kg/day in ≤31 weeks adjusted (↑ risk of ototoxicity)
- Neonates: 0.5-1 mg/kg/dose q6-8h
- Children: 0.5-1 mg/kg/dose q6-24h
  - Usual range 0.5-2 mg/kg/dose, rarely will use 3 mg/kg/dose for renal impairment (e.g., “diuretic challenge”)
  - Max 6 mg/kg/dose (200 mg/dose, 10 mg/kg/day)
- Adults: 20-80 mg/dose q6-12h
  - Titrate by 20 mg/dose q1-2h until desired effect seen
  - Max 200 mg/dose (≤600 mg/day)
Continuous
- Children: 0.05-0.4 mg/kg/h
  - May load with 0.1 mg/kg IV bolus
- Adults: 10-40 mg/h
  - May load with 20-40 mg IV bolus

Bumetanide (Bumex®)

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Dose conversion: good bioavailability (>80%); assume 1:1 potency IV:PO

Enteral

Onset of diuresis 30-60 min, with peak in 1-2 hours and duration of 4-6 hours
Neonates: 0.01-0.05 mg/kg q12-48h
Infants/Children: 0.01-0.1 mg/kg q6-24h
- Max 10 mg/day; study of infants (0-6 mo) showed no improvement in diuretic effect above 0.04 mg/kg/dose
Adults: 0.5-1 mg q8-24h
- Max 10 mg/day

Intravenous (IV)

Onset of diuresis within minutes, with peak in first 30 min
Intermittent
- Neonates: 0.01-0.05 mg/kg q12-48h
- Infants/Children: 0.01-0.1 mg/kg/dose q6-24h
  - Max 10 mg/day; study of infants (0-6 mo) showed no improvement in diuretic effect above 0.04 mg/kg/dose
- Adults: 0.5-1 mg q8-24h
  - Max 10 mg/day
Continuous
- Infants/Children: 5 mcg/kg/h
  - Titrate by 5 mcg/kg/h
  - Usual range 5-15 mcg/kg/h
  - Max 30 mcg/kg/h
- Adults: 0.5-2 mg/h
  - May load with 1 mg IV bolus
  - Max 5 mg/h

Ethacrynic acid (Edecrin®)

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warning

Has greater ototoxicity compared to other loop diuretics. Reserve for patients with sensitivity to sulfonamide-based loop diuretics (furosemide, bumetanide, torsemide) who are refractory to other diuretics.

Enteral

Start with daily dosing; later, may dose daily or divide BID (or even TID in children)
Children: 1 mg/kg q24h
- Titrate q48-72h
- Max 3 mg/kg/day (400 mg/day)
Adults: 25-50 mg q24h
- Titrate q24h
- Usual range 50-200 mg
- Max 400 mg/day

Intravenous (IV)

danger

Risk of thrombophlebitis; limit IV injections to single doses if possible and rotate IV access if additional doses are necessary

Intermittent
- Children: 0.5-1 mg/kg/dose q8-24h
  - Max 50 mg/dose
- Adult: 50 mg or 0.5-1 mg/kg x1 dose
  - Max 100 mg x1 dose (if necessary, may do 1 additional dose 8-12 hours later)
Continuous
- Children:
  - 0.1 mg/kg/h
  - Usual range 0.1-0.35 mg/kg/h
  - Max 0.5 mg/kg/h

Thiazide and thiazide-like

tip

enteral equivalents: hydrochlorothiazide 25 mg = metolazone 2 mg = chlorthalidone 12.5 mg

Chlorothiazide (Diuril®)

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Enteral

Children:
- 5-10 mg/kg q6-12h
- Max 40 mg/kg/day (2000 mg/day)
Adults:
- 500-2000 mg q12-24h
- Max 2000 mg/day

Intravenous (IV)

warning

Avoid extravasation, extremely irritating to tissues.

Children:
- 2.5-10 mg/kg q6-12h
- Typical 5-10 mg/kg q6-8h
- Max 40 mg/kg/day (2000 mg/day)
Adults:
- 500 mg q6-24h
- Max 2000 mg/day

Hydrochlorothiazide (HCTZ)

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Enteral

May dose daily or divide BID
Age <6 months: 1-3 mg/kg/day
- Max 37.5 mg/day
Age ≥6 months to <2 years: 1-2 mg/kg/day
- Max 37.5 mg/day
Age ≥2 to <12 years: 1-2 mg/kg/day
- Max 100 mg/day
Age ≥12 years: 1-2 mg/kg/day
- Max 200 mg/day
Adults: 25-100 mg/day
- Max 200 mg/day

Metolazone (Zaroxolyn®)

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Enteral

May dose daily or divide BID
Infants/Children: 0.2-0.4 mg/kg/day
- Lower doses (0.05-1 mg/kg q24h) may be effective
- Max 20 mg/day
Adults:
- 2.5-5 mg/day
- Max 20 mg/day

Chlorthalidone (Hygroton®, Thalitone®)

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Enteral

Children: 0.3 mg/kg daily
- Usual range ≤25 mg/day; >25 mg → ↑ risk of side effects without much improvement in diuretic effect
- Max 2 mg/kg/day (50 mg/day)
Adults: 12.5-25 mg daily (or daily PRN)
- Max 200 mg/day

Potassium-sparing diuretics

tip

Enteral equivalents: spironolactone 12.5 mg = amiloride 5 mg = eplerenone 25 mg

Spironolactone (Aldactone®, CaroSpir®)

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Enteral

warning

Liquid formulation (CaroSpir®) is not equivalent to tablet (15-37% higher serum concentration vs tablet); decrease doses by ~20% when using the liquid formulation

Sometimes packaged with HCTZ (Aldactazide®)
Neonates: 1-3 mg/kg/day
- May dose daily or divide BID
Infants/Children: 1-3.3 mg/kg/day
- May dose daily or divide BID/up to q6h
- Max 100 mg/day
Adults: 12.5-25 mg q24h
- Titrate every 2-4 weeks (weekly if severe asymptomatic hypertension)
- Usual range 25-50 mg
- Max 100 mg/day

Amiloride (Midamor®)

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Enteral

May dose daily or divide BID
Children:
- 0.3-0.625 mg/day (≤5 mg/day)
- Titrate by ≤5 mg/day
- Max 20 mg/day
Adults:
- 5 mg/day
- Titrate by ≤5 mg/day
- Max 20 mg/day