Research Abstract |
Recently, Propionibacterium acnes, methicfllin-resistant Staphylococcus epidermidis, methicillin-resistant Staphylococcus aureus and gram-positive organisms have become important pathogens in bacterial endophthalmitis after extracapsular cataract extraction with posterior chamber lens implantation or vitrectomy for proliferative diabetic retinopathy. The incidence of viral retinitis and endogenous fungal endophthalmitis has increased with use of immunosuppressive therapy. Therefore the treatment of these disorders is now very important. The treatment with systemically administered antimicrobials is often unsuccessful because of poor penetration into the eye. Therefore, intravitreal administration is needed. The purpose of the present research is to establish the nontoxic intravitreal dose of antimicrobials. Effects of topically applied antimicrobials on the retina were studied in rabbits with electroretinogram, visually evoked potential and histological examination after intravitreal i
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njections or irrigation of an antimicrobial-containing solution. We also studied the intraocular penetration of intravenously injected antimicrobials such as flomoxef, lomefloxacin, ceftazidime and fluconazole under surgical conditions, and intraocular pharmacokinetics of flomoxef, lomefloxacin, ceftazidime and BVaraU after a single intravitreal injection. Our recommended one-shot intravitreal dose of antimicrobials for clinical use is as follows : flomoxef 200-400 mug/0.1 ml, lomeflox ; acin 200 mug/0. I ml, norfloxacin 50 mug/0. I ml, ceftazidime 200-400mug/0. I ml and ganciclovir 100-200mug/0.1 ml. Our recommended concentration of antimicrobials for an intravitreal irrigation solution during vitrectomy is as follows : ofloxacin 50 mug/ml and BVaraU 20 mug/ml. The intravitreal flomoxef or ceftazidime concentration was low in nominal eyes one hour after intravenous injection, and high in vitrectomized eyes when injected immediately after surgery. The lorinefloxacin concentration was low in normal eyes and also in vitrectomized eyes. The high intraocular penetration of fluconazole-was observed in normal eyes as well as in vitrectomized eyes after intravenous administration. Intraocular penetration of fluconazole was not increased by vitrectomy. The half-life in the vitreous humor after intravitreal injection was 4.4 hours for flomoxef, 2.8 hours for lomefloxacin, 7.4 hours for ceftazidime and 2.5 hours for B VaraU. Less
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