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—We appreciate the comments on our work by Dr Flynn and colleagues and agree that the current trend is toward the use of vancomycin and aminoglycoside for intravitreal injection rather than cefazolin and an aminoglycoside. This change in choice of drugs occurred because vancomycin has superior activity against streptococci and methicillin-resistant staphylococci.We used cefazolin in our studies as a model to investigate pharmacokinetic changes of a first-generation cephalosporin after inflammation and surgery. We have demonstrated that inflammation increases the half-life of the drug after intravitreal injection, while vitrectomy decreases it.1 Enhanced drug penetration over time into inflamed eyes after multiple intravenous doses had not been previously defined, and our findings point to the possible importance of this phenomenon for other drugs available for treatment of endophthalmitis.2 Taking these studies together, we now know that we can achieve therapeutic levels of cefazolin in the vitreous cavity
Meredith TA, Martin D, Gardner SK, Wilson LA, Aguilar HE. Endophthalmitis Therapy: Changing Antibiotic Sensitivity Patterns and Current Therapeutic Recommendations-Reply. Arch Ophthalmol. 1991;109(2):176. doi:10.1001/archopht.1991.01080020021013