Continuous infusion of ceftazidime with an elastomeric infusion device

The serum disposition, antimicrobial activity, and stability of ceftazidime continuously infused with an elastomeric infusion device (Homepump, Block Medical) were studied. Twelve healthy adult volunteers were given a 500-mg bolus dose of ceftazidime infused i.v. over two minutes, followed by a continuous i.v. infusion of 3 g over 24 hours. Blood samples were drawn five minutes before and at intervals up to 24 hours after the start of the bolus infusion. Samples were collected from the infusers immediately before and at the end of the 24-hour infusion. Infusers were insulated with ice packs. Ceftazidime concentrations were determined by high-performance liquid chromatography. Minimum inhibitory concentrations (MICs), serum inhibitory titers (SITs), and serum bactericidal titers (SBTs) were determined by the microdilution technique. Mean +/- S.D. serum ceftazidime concentrations ranged from 39.50 +/- 6.92 micrograms/ml at peak (30 minutes after the start of the bolus infusion) to 15.30 +/- 2.83 micrograms/mL at trough (24 hours after the start). The ceftazidime MIC for Pseudomonas aeruginosa was 1 microgram/mL; this MIC was exceeded 100% of the time. Serum ceftazidime concentrations achieved a median SIT and SBT of 1:32 and 1:16, respectively, at 30 minutes and 1:8 and 1:8, respectively, at 24 hours. Six infusers met or exceeded the 24-hour infusion time; ceftazidime was stable in these infusers. A 500-mg i.v. bolus of ceftazidime followed by a continuous infusion (3 g over 24 hours) delivered by an elastomeric infusion device produced serum drug concentrations that were constantly above the MIC for P. aeruginosa and maintained serum bactericidal activity against that organism. Adequate stability of ceftazidime was ensured by placing an ice pack next to the infuser.