Pharmacokinetics of ceftazidime in acutely ill hospitalised elderly patients

The i.v. and i.m. dose pharmacokinetics of ceftazidime 1 g b.i.d. were investigated in steady state in 52 consecutive cases of hospitalised patients with underlying diseases and serious supervening bacterial infections. Following i.v. bolus injection, serum concentrations of greater than 4 mg/l persisted for 8 h in all patients. Compared to values found in younger patients studied previously, clearance was markedly reduced in the elderly, t1/2 beta more than doubled, the area under the curve four times enlarged and the apparent volume of distribution reduced. The values obtained in serum after i.m. injection were similar, though the peak concentration was delayed by about 2 h. The serum uptake was approximately 70%, and serum concentration was greater than 4 mg/l for 8 h. The concentrations in tissue fluid after i.v. administration were similar to those in serum, but the penetration into tissue fluid was slower and only 20% of that reported previously for young people. The elimination was slow, with greater than 4 mg/l maintained for 7 h. Tissue concentrations after i.m. injection were almost comparable with those after i.v. injection, but lagged behind by about 1 h. In conclusion, suitable concentrations in blood and tissue are attained with 1 g ceftazidime b.i.d., whether administered by the i.v. or i.m. route.