Pharmacokinetics
Molecular weight (daltons)             330.7
% Bioavailability    47-70%
Bioavailability with end-stage renal disease   43 - 46%
% Protein binding                      91–99
Volume of distribution (L/kg)          0.07 – 0.2Volume of distribution may be higher in patients with cirrhosis or nephrotic syndrome
Excretion
% Excreted in urine (% of total dose)   60 - 90
% Excreted unchanged in urine (% of total dose)         53.1 - 58.8 
% Excreted in feces (% of total dose) 7 - 9
% Excreted in bile (% of total dose) 6 - 9
Approximately 10% is metabolized by the liver in healthy individuals, but this percentage may be greater in individuals with severe kidney failure 
Renal clearance (mL/min/kg)  2.0
Elimination half-life (hrs)   2Prolonged in congestive heart failure (mean 3.4 hrs)
Prolonged in severe kidney failure (4 - 6 hrs) and anephric patients (1.5-9 hrs)
Time to peak concentration (hrs)
Intravenous administration    0.3
Oral solution    0.83
Oral tablet     1.45The pharmacokinetics of furosemide are apparently not significantly altered by food.No direct relationship has been found between furosemide concentration in the plasma and furosemide efficacy. Efficacy depends upon the concentration of furosemide in urine. Names
Furosemide is the INN and BAN. The previous BAN was frusemide.
The drug is best not used during pregnancy or in a lactating mare, as it has been shown to be passed through the placenta and milk in studies with other species. It should not be used in horses with pituitary pars intermedia dysfunction (Cushings). Furosemide is detectable in urine 36–72 hours following injection. Its use is restricted by most equestrian organizations. In April 2019, it was announced that Lasix would be banned from use at US racetracks within 24 hours of a horse racing starting in 2021. References
Further reading
Aventis Pharma (1998). Lasix Approved Product Information. Lane Cove: Aventis Pharma Pty Ltd.
Barbara Forney (2007). Understanding Equine Medications, Revised Edition (Horse Health Care Library). Eclipse Press. ISBN 978-1-58150-151-3. External links

"Furosemide". Drug Information Portal. U.S. National Library of Medicine. "Furosemide Injection". MedlinePlus. Lasix and horse bleeding