The stability of ceftazidime solutions (100 and 200 mg/mL) in plastic syringes and glass vials under various storage conditions was examined. Solutions of ceftazidime 100 and 200 mg/mL in sterile water were placed in polypropylene plastic syringes or glass vials and stored (1) at 21-23 degrees C for up to 8 hours, (2) at 4 degrees C for up to 96 hours, (3) at -20 degrees C for 28 days and then 21-23 degrees C for up to 8 hours, (4) at -20 degrees C for 28 days and then 4 degrees C for up to 96 hours, (5) at -20 degrees C for 91 days and then 21-23 degrees C for up to 8 hours, or (6) at-20 degrees C for 91 days and then 4 degrees C for up to 96 hours. Samples were withdrawn from each syringe and vial at designated times and assayed by high-performance liquid chromatography. Solutions were judged to be stable if drug concentrations remained above 90% of the initial values. The number of particles in each container under each storage condition was also evaluated. Ceftazidime was stable under all storage conditions. In all containers, particulate matter was within USP specifications for small-volume injections, with no change in particle count as a result of the freezing and thawing. Ceftazidime in sterile water in either glass vials or plastic syringes is stable for 8 hours at room temperature or 96 hours at 4 degrees C when such storage occurs (1) immediately after constitution, (2) after 28 days of frozen storage, or (3) after 91 days of frozen storage.