BIOAVAILABILITY, PHARMACOKINETICS, AND PHARMACODYNAMICS OF TORSEMIDE AND FUROSEMIDE IN PATIENTS WITH CONGESTIVE-HEART-FAILURE

The bioavailability, pharmacokinetics, and pharmacodynamics of torsemi de (10 mg orally and intravenously) and furosemide (40 mg orally and 2 0 mg intravenously) were determined in a randomized crossover clinical trial in 16 patients with compensated congestive heart failure, Torse mide (time to reach maximum concentration [t(max)], 1.1 +/- 0.9 hour) was more rapidly absorbed than furosemide (t(max), 2.4 +/- 2.5 hours), the absorption of which was delayed compared with that in healthy vol unteers, Bioavailability of torsemide was also greater and less variab le than that of furosemide, All four treatments yielded comparable cha nges from baseline in 24-hour electrolyte excretion, Based on the rela tionships between sodium excretion rate and fractional sodium and urin ary drug excretion rate, response to both diuretic agents at the level of the nephron was decreased compared with previous studies with heal thy subjects. Assessment of the clinical relevance, if any, of the dif ference in the variability of absorption warrants further study.