RT Journal Article SR Electronic T1 Studies on the renal excretion mechanisms of cefadroxil. JF Drug Metabolism and Disposition JO Drug Metab Dispos FD American Society for Pharmacology and Experimental Therapeutics SP 447 OP 450 VO 22 IS 3 A1 L Granero A1 M J Gimeno A1 F Torres-Molina A1 J Chesa-Jiménez A1 J E Peris YR 1994 UL http://dmd.aspetjournals.org/content/22/3/447.abstract AB The mechanisms of renal excretion of cefadroxil were investigated in conscious rats. The drug was intravenously infused at several infusion rates (0.27, 1.08, 5.40, 12.00, and 31.35 mg/hr), and the total and renal clearances were determined after the steady-state was reached. Renal clearance accounted for approximately 91% of total clearance. Renal clearance of cefadroxil increased from 2.51 +/- 0.39 to 3.57 +/- 0.43 ml/min as the steady-state cefadroxil plasma concentration increased from 1.7 +/- 0.3 to 24.4 +/- 3.8 micrograms/ml, and this has been attributed to a saturable renal tubular reabsorption of the antibiotic. The ratio of unbound cefadroxil renal clearance to glomerular filtration rate was larger than unity, which indicates that the antibiotic also undergoes active renal tubular secretion. When cefadroxil was administered together with cephalexin, an increase in the renal clearance of cefadroxil was observed, which has been attributed to a competitive inhibition of the tubular reabsorption of cefadroxil by cephalexin. A pharmacokinetic model for the renal excretion of cefadroxil was developed, and mathematical expressions showing the relationship between renal clearance and steady-state plasma concentration were deduced.