An in vitro study of ceftazidime and vancomycin concentrations in various fluid media: implications for use in treating endophthalmitis.

作者：Alvin KH Kwok, Mamie Hui, Chi Pui Pang, Raphael C.Y. Chan, Siu Wai Cheung, Cynthia M S Yip, Dennis S.C. Lam, Augustine F. Cheng · 发表于：PubMed · 年份：2002 · 被引用次数：94 · 研究领域：Ocular Infections and Treatments、Retinal and Macular Surgery、Intraocular Surgery and Lenses

PURPOSE: To investigate the precipitation process of a mixture of vancomycin and ceftazidime by equilibrium dialysis and determine its subsequent effect on the level of free antibiotics for treatment of endophthalmitis. METHODS: Concentrations of vancomycin and ceftazidime in an equilibrium dialysis chamber were measured during the equilibrium process by high-performance liquid chromatography. Normal saline (NS), balanced salt solution (BSS), and vitreous were used separately as the medium of dialysis. RESULTS: Precipitation of ceftazidime occurred at 37 degrees C but not at room temperature and did not affect the pH of the medium. It formed precipitate on its own or when mixed with vancomycin in all the three media of NS, BSS, and vitreous. More precipitation was formed if ceftazidime was initially prepared in BSS than in NS. After 168 hours in the dialysis chambers, ceftazidime prepared in NS precipitated to 54% of that in vitreous, compared with 88% if prepared in BSS. At 48 hours, ceftazidime prepared in NS decreased from an initial concentration of 137.5 to 73.4 microg/mL in vitreous medium and to 6.3 microg/mL if prepared in BSS. Precipitation of vancomycin was negligible. CONCLUSIONS: Based on this in vitro investigation, ceftazidime precipitates in vitreous at body temperature, regardless of the presence of vancomycin. NS is preferred to BSS as a preparation medium for antibiotics for intravitreal injection, because the extent of ceftazidime precipitation is less. How...