Bioavailability, pharmacokinetics, and pharmacodynamics of torsemide in patients with cirrhosis.

The bioavailability, pharmacokinetics, and pharmacodynamics of torsemide (10 mg orally and intravenously) were determined in a randomized crossover clinical trial with 12 patients with ascites caused by cirrhosis. Torsemide was rapidly absorbed with a bioavailability of 96.3% (confidence interval, 84% to 109%). Compared with healthy subjects, patients with cirrhosis exhibit a decrease in nonrenal clearance and increases in bioavailability, volume of distribution, renal clearance, elimination half-life, and percentage of the dose excreted into the urine. A greater proportion of the dose is delivered to the site of action over a more prolonged period of time. In spite of a shift of the pharmacodynamic curve to the right in patients with cirrhosis, there was no significant difference in natriuresis. Pharmacokinetic changes of torsemide in cirrhosis therefore compensate for the pharmacodynamic abnormality.