Clinical results and pharmacokinetics of ceftazidime treatment in patients with cystic fibrosis.

Ceftazidime (50 mg/kg/8 h) alone or combined with tobramycin (5 mg/kg/8 h) was given to 14 patients with cystic fibrosis. Ten courses were given with ceftazidime alone and 6 courses with a combined therapy. All patients were chronically colonized with Pseudomonas aeruginosa and were hospitalized because of lower respiratory tract infections. Using an agar-well diffusion technique, the concentration of ceftazidime was determined in serum and sputum. The mean (+/- S.E.M.) peak serum concentration of ceftazidime was 142 +/- 16 mg/l during the second to third day of treatment and 114 +/- 18 mg/l on the fifth to sixth day of treatment. In the combined therapy the corresponding values were 104 +/- 20 mg/l and 74 +/- 8 mg/l, respectively. The range of the mean half life was 1.2 to 1.4 h. The maximum concentration of ceftazidime in sputum was usually obtained 1 h after the infusion, ranging from 0.7 to 9.8 mg/l. All patients improved during treatment. Non-mucoid strains of Ps. aeruginosa were eradicated in nearly half of the courses, mucoid strains less often. No side reactions were noted.