Furosemide kinetics and dynamics in rats and humans

Area of Science:

• Pharmacology
• Nephrology
• Comparative Physiology

Background:

• Furosemide is a widely used diuretic.
• Understanding species-specific responses is crucial for drug development and application.
• Previous studies have indicated potential differences in furosemide handling between species.

Purpose of the Study:

• To compare the initial pharmacokinetics and pharmacodynamics of furosemide (F) in rats and humans following intravenous administration.
• To identify and quantify species-specific differences in drug excretion, distribution, and physiological response.
• To explore potential standardization methods for interspecies comparison.

Main Methods:

• Intravenous administration of increasing furosemide doses to rats and humans.
• Measurement of serum drug concentrations and renal excretion rates.
• Calculation of pharmacokinetic parameters, including volume of distribution.
• Assessment of diuretic and natriuretic responses and drug potency.

Main Results:

• Rats exhibited a higher weight-related initial renal excretion rate of furosemide, while humans showed higher serum concentrations at 30 minutes.
• The volume of distribution for furosemide was significantly larger in rats (44% greater).
• Maximal diuretic and natriuretic responses were 5-6 times higher in rats, but potency was 230 times lower.

Conclusions:

• Significant species differences exist in furosemide pharmacokinetics and pharmacodynamics between rats and humans.
• Standardization of pharmacokinetic analysis using effective renal plasma flow (ERPF) and dynamic analysis using glomerular filtration rate (GFR) can reconcile these interspecies differences.
• These findings highlight the importance of species-specific considerations in diuretic drug research.