Comparison of the pharmacokinetics and pharmacodynamics of torasemide and furosemide in healthy volunteers.

The pharmacodynamic effects and the pharmacokinetic parameters of torasemide (1-isopropyl-3- ([4-(3-methyl-phenylamino)pyridine]-3-sulfonyl)urea) 20 mg and furosemide 40 mg were compared after oral and intravenous administration in 6 healthy volunteers. The plasma elimination half-life for i.v. and oral torasemide was 2.2 h and 2.8 h, its bioavailability after oral administration was 91%, about 25% of the total body clearance was due to renal excretion both after iv. or oral application. For furosemide, a plasma elimination half-life of 0.6 h for i.v. and 0.8 h for oral application was found. The bioavailability was 40%, and about 62% of the drug was excreted via the kidney. Both drugs produced a similar diuretic and natriuretic effect. However, torasemide showed an increased duration of action compared to furosemide and a higher relation between urinary Na and K excretion, both after i.v. and oral administration, suggesting less loss of potassium after To. Both agents were well tolerated.