Two sodium carbonate formulations of ceftazidime (Tazidime and Tazicef) and a new arginine formulation (Ceptaz) were evaluated for gas production and bubble formation within the drug reservoir and extension tubing of a portable infusion pump during a 24-hour delivery cycle. Triplicate samples of each brand of ceftazidime were studied under identical conditions. All formulations were constituted and diluted with sterile water for injection to a concentration of approximately 33 mg/mL, drawn into syringes, and expelled into infusion-pump drug reservoirs. Triplicate samples of degassed Tazidime and Tazicef were evaluated in the same manner. In one set of triplicate experiments, reservoirs for each formulation were attached to portable infusion pumps immediately after filling at room (23 degrees C) temperature and were programmed to deliver 25 mL over one hour every eight hours for a 24-hour delivery cycle. In a second experiment, reservoirs containing triplicate samples of each product were refrigerated (3 degrees C) for 24 hours before they were attached to the pumps for dose delivery. Visual observations were made for all pumping devices. In addition, multiple vials of each formulation were constituted, and the headspace pressure of the various formulations was monitored to compare the pressure build-up due to carbon dioxide. The presence of carbon dioxide was confirmed by gas chromatography. Pressure build-up due to carbon dioxide formation occurred in the ceftazidime sodium carbonate vials only. The sodium carbonate formulations required degrassing to reduce gas and bubble formation to a manageable level after constitution. Additionally, drug was lost because of spewing of some samples during withdrawal from the vial.(ABSTRACT TRUNCATED AT 250 WORDS)