Pharmacokinetics and saluretic effect of muzolimine in severe cardiac failure

Pharmacokinetics and effects on renal electrolyte excretion of a new diuretic drug, muzolimine (Bay g 2821), were investigated in 6 patients with severe congestive cardiac failure (New York Association classification Groups III and IV). After a single oral dose of 30 mg muzolimine, mean urinary excretion rate of sodium increased from 1.37 to 4.30 mmol/hour during the initial 24 hours, that of chloride from 0.86 to 3.97 mmol/hour, that of potassium from 1.23 to 1.63 mmol/hour, and that of water from 25.8 to 49.9 ml/hour. The saluretic effect lasted for 10 to 14 hours in 1 patient, 14 to 24 hours in 2, and more than 24 hours in 3 patients. Peak plasma concentrations of muzolimine occurred 1 to 7 hours after administration and averaged 487 ng/ml (range 268 to 868). Mean biological half-life of muzolimine in plasma was 14.3 hours (range 9.0 to 21.2 hours). The saluretic effect of muzolimine in congestive cardiac failure, thus, is of long duration, which may be explained by its long biological half-life.