Diuretic effect and duration of action of a single intravenous dose of furosemide in uremia and myocardial infarction.

Furosemide was given in a single dose of 80 mg to 10 normal subjects, 10 uremic and 6 subjects with uncomplicated myocardial infarction. Furosemide overall effects and rates of urine flow, sodium and potassium excretion in different pathophysiological states were compared. During 24 hours furosemide resulted in a two-fold increase in urine flow in both normal and myocardial infarction subjects when compared to 1.4 in uremic patients. Furosemide produced nearly a two-fold increase in 24 hours. Na excretion was in all the three groups studied. K excretion in 24 hours was higher in myocardial infarction patients than uremics and normals, but the difference was not significant (p less than 0.05). Rate-time plot for urine, Na or K excretion showed that the decline was slower in uremic or myocardial infarction patients than in normal subjects. The smaller decay constants for effect in both uremic and myocardial infarction subjects were indicative of longer duration of action of furosemide in these patients. No correlation was observed between overall Na or K excretion after furosemide and creatinine clearance. Changes in renal function or renal hemodynamics produced decreased but prolonged effects of furosemide and eventually the overall diuretic effect of the drug was slightly altered.