Torasemide is a new
loop diuretic that differs from others in this class in that only 20% of the
drug is excreted unchanged in the urine with the remaining 80% being eliminated by hepatic metabolism. The large component of nonrenal clearance would predict that
torasemide would have only minimal accumulation and prolongation of half-life in patients with
renal insufficiency, and this proves to be the case. In contrast, in patients with
liver disease, impairment of hepatic elimination causes accumulation of
torasemide in plasma with prolongation of half-life. In addition, in
cirrhosis, there is increased elimination of unchanged
drug into the urine compared to healthy controls. In patients with
renal insufficiency, response to remaining nephrons is normal as has been observed with other
loop diuretics. In patients with
cirrhosis and in those with
congestive heart failure, response is diminished, again as has been observed with other
loop diuretics. Interestingly, in patients with
cirrhosis, the increased delivery of
drug into the urine is sufficient to compensate for the decreased pharmacodynamics of response so that overall response is similar to that which occurs in health subjects.