Chronopharmacological study of furosemide in human subjects.

The present study was undertaken to determine whether the diuretic effects of furosemide depend on the administration time or not. After furosemide 20 mg or a placebo was administered intravenously in 12 human subjects at 09h00 or at 21h00, urine volume and urinary excretion of sodium, chloride and furosemide were determined for 3 h. There were no significant differences in the amount of urine, or of urinary excretion of sodium and chloride between when a placebo was given at 09h00 and when it was given at 21h00. When furosemide was administered at 21h00, the urine volume and urinary excretion of sodium, chloride and furosemide during the first 60 min were significantly greater than those, when the drug was administered at 09h00. There was a marked correlation between the urinary output of furosmeide and the urine volume, urinary sodium and urinary chloride. These results suggest that the diuretic effects of furosemide vary with the time of administration and the observed variations are mainly dependent on the amount of furosemide secreted into urine.