CONTINUOUS-INFUSION OF CEFTAZIDIME WITH AN ELASTOMERIC INFUSION DEVICE

The serum disposition, antimicrobial activity, and stability of ceftaz idime continuously infused with an elastomeric infusion device (Homepu mp, 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 s amples 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 al the end of the 24-hour infusion. I nfusers were insulated with ice packs. Ceftazidime concentrations were determined by highperformance liquid chromatography. Minimum inhibito ry concentrations (MICs), serum inhibitory titers (SITs), and serum ba ctericidal titers (SBTs) were determined by the microdilution techniqu e. Mean +/- S.D. serum ceftazidime concentrations ranged from 39.50 +/ - 6.92 mu g/mL at peak (30 minutes after the start of the bolus infusi on) to 15.30 +/- 2.83 mu g/mL at trough (24 hours after the start). Th e ceftazidime MIC for Pseudomonas aeruginosa was 1 mu g/mt; this MIC w as exceeded 100% of the time. Serum ceftazidime concentrations achieve d a median SIT and SET of 1:32 and 1:16, respectively, at 30 minutes a nd 1:8 and 1:8, respectively, at 24 hours. Six infusers met or exceede d 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 produc ed serum drug concentrations that were constantly above the MIG: for P . aeruginosa and maintained serum bactericidal activity against that o rganism. Adequate stability of ceftazidime was ensured by placing an i ce pack next to tile infuser.