Concentration relationships of cefaclor in serum, interstitial fluid, bile, and urine of dogs

The concentrations of cefaclor in the serum, urine, bile, and tissue fluids of the abdominal wall, kidney, and liver of dogs were compared over a 4-h period after oral administration of a single dose of this drug. The concentration of cefaclor in the soft-tissue interstitial fluid peaked 2 h after administration, thereby demonstrating a diffusion rate similar to those of other cephalosporins. Both urine and bile concentrations greatly exceeded the serum levels, whereas none of the tissue fluid concentrations were greater than the serum concentrations at the times of measurement.