Study objective: To compare the efficacy of constant-infusion ceftazidime (CTZ) with that of traditional intermittent dosing in a pilot trial.
Design: Prospective, crossover trial.
Subjects: Five adults with cystic fibrosis requiring intravenous antibiotic therapy for pulmonary exacerbations of the disease.
Interventions: Patients were initially treated with standard CTZ 2 g 3 times/day for 10 days. At the next hospitalization patients were crossed over and CTZ was administered as a constant infusion at a rate determined to achieve a serum concentration 6.6 times the minimum inhibitory concentration (MIC) of the least susceptible Pseudomonas aeruginosa isolate.
Measurements and main results: The pharmacokinetics of CTZ were determined, as were MICs for all P. aeruginosa isolates. Outcome parameters of interest were changes with therapy in white blood cell count, P aeruginosa density in sputum, and pulmonary function test results. Differences in these parameters for the two forms of administration were not significant. With the exception of one patient who received 6 g/day with both regimens, the average reduction in dosage with the constant infusion was 50%.
Conclusion: These preliminary data suggest that constant-infusion CTZ may be as safe and efficacious as intermittent dosing.