Pharmacokinetics and pharmacodynamics of furosemide in geriatric patients

Abstract

Twenty geriatric patients with multiple diseases were administered a single intravenous dose of 40 mg furosemide. Furosemide plasma and urine concentrations were measured using a thin-layer chromatography method and were fitted to an open 2-compartment model. Furosemide half-life was prolonged two-fold in the elderly patients compared with a control group of younger adults. In the same way renal clearance and total clearance were markedly reduced in the geriatric group. The non-renal clearance and the volume of distribution were not significantly altered. There were many significant correlations between clinical and biochemical data and pharmacokinetic parameters, especially between blood pressure and the area under the curve (AUC O-∞), total clearance and non-renal clearance of furosemide. Our data suggest a special function of α-2-globulins in binding of furosemide. Renal function (i.e. creatinine clearance) was shown to be an important parameter for estimating the elimination rate of furosemide. In addition, pharmacodynamic action (volume of excreted urine) was closely correlated with the elimination rate: furosemide is apparently triggering its own elimination.