[Features of the pharmacodynamics and pharmacokinetics of furosemide upon long-term administration in rats].

Long-term administration of furosemide in rats (single daily dose, 20 mg/kg for 7 days) was accompanied by a decrease in the diuretic, natriuretic, and kaliuretic effects, which was related to a decrease in the rate of renal metabolism and excretion. It was found that more than 85% of the daily excretion of sodium takes place within the first 6 h after furosemide administration (on the background of comparable excretion of the drug), while the elimination of potassium and water during one day is more uniform. It is established that the long-term administration of furosemide leads to a decrease in the drug excretion during the first 6-h period, followed by a growth in the subsequent 18-h period of time. These changes in the daily dynamics of drug excretion account for the analogous trends in the elimination of water and electrolytes.