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S. Lee, I. Park, S. Kim; Vancomycin and Ceftazidime Precipitation Upon Intravitreal Injection During Pars Plana Vitrectomy. Invest. Ophthalmol. Vis. Sci. 2008;49(13):874.
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The white precipitates appeared upon Intravitreal injection of vancomycin and ceftazidime during pars plana Vitrectomy. The authors investigate the causes of the precipitation.
74 years old patient was operated because of endophthalmitis after cataract surgery. Pars plana vitrectomy was performed and vancomycin (1mg/0.1ml) and ceftazidime (2mg/ml) were injected. As soon as the injection, the red reflex of the eye was disappeared and white huge precipitates were observed at the posterior pole although the different syringe and needle were used for each antibiotics. Serial dilution technique was used to define the minimum concentration of the antibiotics to be precipitated. The amount of precipitation depending on the kinds, temperature, and acidity of media were investigated. Balanced salt solution plus and normal saline were aliquoted into the 16 wells ( 4, 3, 2, 1 ml) and incubated at 37 °C and 3 °C respectively. Vancomycin (1mg/0.1ml) and Ceftazidime (2mg/0.1ml) were administered.
2 months after Vitrectomy, the visual acuity of the patient was recovered upto 20/20 and the retinal toxicity was not observed. Two-fold dilutions of ceftazidime (20-0.2mg/ml) formed precipitate higher than 0.63 mg/ml when mixed with vancomycin (10mg/ml), and vancomycin (10-0.1mg/ml) formed precipitate higher than 5mg/ml when mixed with ceftazidime (20mg/ml). When mixed the two-fold diluted antibiotics each other, precipitations were formed at higher than 10 and 5mg/ml of ceftazidime and vancomycin, respectively. The extend of precipitation increased in the lower temperature, less amount, and saline media. However, pipetting the media after administration of vancomycin or ceftazidime make the media of the antibiotics mixture unprecipitated.
Even after complete vitrectomy, the precipitation could appear at the injection of vancomycin and ceftazidime. The Intraoperative formation of precipitate was associated with diffusion rate of antibiotics in the media and might increase in the lower temperature, less volume of media and higher concentration of antibiotics.
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