Dosing

Notes

Loop diuretics (Na, K, 2 Cl) (thick ascending limb of Loop of Henle)

Furosemide

Starting dose 20-40 mg (IV)
Max single dose 40-80 mg
Max daily dose 600 mg

PO bioavailability low (50%) and extremely variable - 10-100%

6 hour duration

Excrete 20-25% of total filtered Na (first-line)

Reduced PO absorption with intestinal mucosal edema → IV route preferred if very fluid overloaded

Torsemide

Starting dose 5-10 mg
Max single dose 100 mg
Max daily dose 200 mg

Long half-life

Good PO bioavailability

Bumetanide

Starting dose 0.5-1 mg
Max single dose 5 mg
Max daily dose 10 mg

Good PO bioavailability

Aldosterone antagonist (K+ sparing) (cortical collecting tubule)

Spironolactone

(eplenerone fewer side effects, more $)

Starting dose 12.5 – 25 mg QD
Double after 4 weeks if K < 5.0

(Aldactone:Lasix = 100:40 for electrolyte balance)

Recommended in (improves remodeling):

• NYHA II, LVEF < 30%
• NYHA III-IV, LVEF < 35%
• STEMI, LVEF < 40%

Excrete 1-2% of total filtered Na

30% reduction in mortality for HFrEF

Thiazide diuretics (Na, Cl) (distal convoluted tubule)

Metolazone (PO only)

(used on top of loop diuretic)

Low dose (< 5 mg) effective

Up to 250 mg

PO thiazide should precede IV loop diuretic by 2-5 hours

Also acts in proximal tubule - better than other thiazides at diuresing with low GFR

Excrete 3-5% of total filtered Na

Distal tubule can reabsorb 75-80% of Na from the loop of Henle