—We thank Fiscella for his interest in our article and for his thoughtful comments. We agree that physical incompatibility of drugs used together in injections is often overlooked. However, we do not mix drugs in the same syringe. It is our practice and our recommendation to administer intravitreous injections using separate syringes and needles. Each drug is injected very slowly to allow for mixing with the fluid in the vitreous cavity. Several patients (only a few of whom have had their case histories published1,2) have been treated with vancomycin and ceftazidime using this technique, and no precipitates or any evidence of toxic effects have been noted. Therefore, we do not think that microprecipitation is a significant problem and we continue to recommend the combination of vancomycin and ceftazidime for the treatment and prophylaxis of endophthalmitis.
Campochiaro PA, Green WR. Physical Incompatibility of Vancomycin and Ceftazidime for Intravitreal Injection-Reply. Arch Ophthalmol. 1993;111(6):730. doi:10.1001/archopht.1993.01090060016002