Meredith T A
Anheuser-Busch Eye Institute, St Louis University, Missouri.
Trans Am Ophthalmol Soc. 1993;91:653-99.
Ceftazidime has pharmacokinetic advantages for treatment of endophthalmitis caused by gram negative-organisms by intravenous administration. Additionally, its spectrum of coverage for these organisms and its relatively low toxicity after intraocular injection are favorable attributes. These studies demonstrate that inflammation leads to a significant reduction of the blood-ocular barriers to ceftazidime. This increased permeability shortens the half-life of the drug after intraocular injection but allows a significant penetration into the eye after a single intravenous dose so that therapeutic levels are achieved. Ceftazidime appears to be removed by both the anterior and the posterior route without active transport. The experiments demonstrate the importance of the vitreous as a barrier to achieving significant concentration of antibiotic within the eye after intravenous administration and confirm the importance of the vitreous in prolonging the half-life of drugs injected intravitreally. Finally the results emphasize that the pharmacokinetic behavior of drugs for treatment of endophthalmitis must be assessed in inflamed eyes both with and without intact vitreous, since these factors play a large role in drug availability and concentration in the vitreous cavity and are the major variables in the clinical setting.
头孢他啶通过静脉给药治疗革兰氏阴性菌引起的眼内炎具有药代动力学优势。此外，它对这些细菌的覆盖范围及其眼内注射后相对较低的毒性都是有利特性。这些研究表明，炎症会导致头孢他啶的血眼屏障显著降低。这种通透性增加缩短了眼内注射后药物的半衰期，但单次静脉给药后能使药物大量渗入眼内，从而达到治疗水平。头孢他啶似乎通过前后途径均被清除，且无主动转运。实验证明了玻璃体作为静脉给药后在眼内达到显著抗生素浓度的屏障的重要性，并证实了玻璃体在延长玻璃体内注射药物半衰期方面的重要性。最后，结果强调，治疗眼内炎药物的药代动力学行为必须在有和没有完整玻璃体的炎症眼中进行评估，因为这些因素在玻璃体腔中药物的可获得性和浓度方面起很大作用，并且是临床环境中的主要变量。
