Recommended Dose for Furosemide (Lasix) Challenge in Adults

The recommended initial dose for a Lasix (furosemide) challenge in adults is 20-40 mg administered intravenously over 1-2 minutes. 1

Initial Dosing Guidelines

For patients with new-onset acute heart failure or those with chronic, decompensated heart failure not receiving oral diuretics, the initial recommended dose is 20-40 mg IV furosemide 2
For patients already on chronic diuretic therapy, the initial IV dose should be at least equivalent to their oral dose 2
In acute pulmonary edema, the usual initial dose is 40 mg injected slowly intravenously (over 1-2 minutes) 1
If a satisfactory response does not occur within 1 hour in acute pulmonary edema, the dose may be increased to 80 mg injected slowly intravenously (over 1-2 minutes) 1

Furosemide should be administered slowly over 1-2 minutes to minimize side effects 1
The drug can be given either as intermittent boluses or as a continuous infusion 2
When administering furosemide, it's important to monitor:
- Symptoms and clinical status 2
- Urine output 2
- Renal function 2
- Electrolytes 2

IV furosemide administration (1.3 mg/kg) results in transient (1-2 hour) worsening of hemodynamics, including increased heart rate, mean arterial pressure, left ventricular filling pressure, and decreased stroke volume 2, 3
Furosemide initially lowers stroke volume and increases systemic vascular resistance 3
Higher loop diuretic doses are associated with worsening renal function during hospitalization 3

For high-dose parenteral therapy, furosemide should be added to either Sodium Chloride Injection, Lactated Ringer's Injection, or Dextrose (5%) Injection after pH has been adjusted to above 5.5 1
When high-dose therapy is needed, administer as a controlled intravenous infusion at a rate not greater than 4 mg/min 1
Furosemide is a buffered alkaline solution with a pH of about 9, and drug may precipitate at pH values below 7 1
Acid solutions, including other parenteral medications (e.g., labetalol, ciprofloxacin, amrinone, milrinone) must not be administered concurrently in the same infusion as they may cause precipitation 1

In patients with diuretic resistance, higher doses may be required, with some studies using continuous infusion at rates of 20 mg/h up to 160 mg/h 4
For elderly patients, dose selection should be cautious, usually starting at the low end of the dosing range 1
In refractory cases, combination therapy with other diuretics may be considered 2, 5

A prompt diuresis typically ensues after IV administration 1
If needed, another dose may be administered in the same manner 2 hours later, or the dose may be increased 1
The lowest mean furosemide urinary excretion rate associated with significant diuresis has been found to be 0.58 ± 0.33 μg/kg/min 6