Distribution of ceftazidime in rat tissues

The pharmacokinetics and tissue distribution of ceftazidime (CFT), a third generation cephalosporin antibiotic commonly used in clinical practice, were investigated in rats after intravenous administration of the antibiotic. Studies using intravenous bolus administration were carried out at two dose levels (5 and 20 mg) of the antibiotic. Results of these studies showed a linear disposition of CFT, no differences between the arterial and venous plasma compartments, and linear distribution in all of the tissues assayed. Experiments carried out under steady-state conditions after constant infusion of the antibiotic showed that CFT distribution was restricted to the extracellular water of the rat tissues, as deduced from the tissue-to-plasma partition coefficients lower than 1 obtained in these experiments. Concentration of CFT in the extracellular water appears to be equal to that of plasma at the same sampling time.