Loop Diuretic

Aka: Loop Diuretic, Furosemide, Lasix, Bumetanide, Bumex, Torsemide, Demadex

1. Indications
   1. Symptomatically reduce pulmonary and peripheral edema
      1. Renal Insufficiency
      2. Congestive Heart Failure
   2. Emergency Management of Pulmonary Congestion (Lasix)
      1. Left Ventricular Dysfunction (CHF)
2. Contraindications
   1. Sulfonamide allergy
3. Mechanism
   1. Potently inhibits reabsorption of sodium and chloride
      1. Action at ascending loop of Henle in glomerulus
   2. Direct Venodilation in Pulmonary edema
      1. Reduces venous return (preload)
      2. Reduces central venous pressure
      3. Synergistic effect with morphine and Nitroglycerin
   3. Reduces Intravascular Volume
      1. Reduces cardiac output
      2. Beware Hypotension in Myocardial Infarction
4. Preparations: Bumetanide (Bumex)
   1. Oral dosing (adults)
      1. Start: 0.5 to 1 mg orally twice daily
      2. Maximum: 10 mg/day
      3. Duration: 4-6 hours
   2. Intravenous dosing (adults)
      1. Start: 1 mg IV/dose (Max: 4-8 mg/dose)
   3. Intravenous Infusion (adults)
      1. Load: 1 mg IV
      2. Rate: 0.5 to 2 mg/hour IV
5. Preparations: Furosemide (Lasix)
   1. Precautions
      1. Lasix (named for LAst SIX) is only effective for 6 hours
      2. Optimal dosing is given at least twice daily (patient otherwise is sodium avid 18 hours/day)
   2. Oral Dosing (adults)
      1. Start: 20-40 mg PO daily to twice daily
      2. Maximum: 600 mg/day (rare to exceed 400 mg/day)
      3. Duration: 6-8 hours
   3. Intravenous Dosing
      1. Administer slowly over 1-2 minutes
      2. Bolus: 20-40 mg IV (0.5-1.0 mg/kg, max 2 mg/kg)
      3. Infusion: 0.25 to 0.75 mg/kg/hour
      4. Onset: Diuresis starts within 10 minutes
      5. Duration: 6 hours (Peak effect in 30 minutes)
   4. Intravenous Infusion
      1. Load: 40 mg
      2. Rate: 10-40 mg/hour IV
6. Preparations: Torsemide (Demadex)
   1. Oral Dosing (adults)
      1. Start: 10-20 mg PO daily
      2. Maximum: 200 mg/day
      3. Duration: 12-16 hours
   2. Intravenous Dosing (adults)
      1. Start: 10 mg IV
      2. Maximum: 100-200 mg/day
   3. Intravenous Infusion (adults)
      1. Load: 20 mg
      2. Rate: 5-20 mg/hour
7. Adverse Effects
   1. Risk of central volume depletion (dehydration)
   2. Hypotension
   3. Electrolyte abnormalities
      1. Metabolic Alkalosis
      2. Hypokalemia
      3. Hypomagnesemia
      4. Hypocalcemia
      5. Hyponatremia
      6. Hyperosmolality
   4. Renal dysfunction
      1. Minimize dosage when starting an ACE Inhibitor
8. Loop Diuretic Resistance Mechanisms
   1. Renal insufficiency
      1. Renal toxin (e.g. NSAID) decreases GFR
      2. NSAIDs
   2. Decreased Diuretic oral absorption
   3. Structural changes in the Kidney
      1. Normal aging
      2. Distal tubular hypertrophy (long term use)
         1. Consider adding a Thiazide Diuretic
         2. Counters distal tubular reabsorption
         3. Significantly boosts Loop Diuretic effect
   4. Increased dietary sodium intake
      1. CHF patient is an avid sodium retainer
      2. Sodium is common in most foods
         1. Chicken Noodle soup = 1200 meq
         2. Milk 122 meq
         3. Big Mac 1010 meq
         4. Canned Spinach 910 meq
9. Precautions
   1. All Loop Diuretics except Torsemide need to be dosed twice daily for effect
   2. Loop Diuretics are associated with significant electrolyte abnormalities and volume depletion (FDA black box warning)