Abstract
Abstract: :
Purpose:There are a few studies about intravitreal triamcinolone (IVT) concentration, but these studies were not focused on the differences between vitrectomized and non–vitrectomized eyes. Therefore we do not know how long the IVT can be present effectively, or when we should reinject the triamcinolone in each case of vitrectomized or non–vitrectomized eyes. We tried to find out the different clearance of IVT between vitrectomized and non–vitrectomized eyes. Methods:84 rabbit eyes were divided into two groups: 42 eyes were undergone vitrectomy and other 42 eyes were not. All eyes had intravitreal injection with 0.1 ml (0.3 mg) of triamcinolone. Every six eyes were undergone enucleation at 1, 2, 4, 7, 12, 20, 30 days after intravitreal injection. The vitreous was prepared for HPLC analysis and triamcinolone was identified and quantified by the HPLC and the fluorescence detector. Results:The half–life of triamcinolone was 1.57 days in vitrectomized eyes and 2.89 days in non–vitrectomized eyes. At 30 days after injection the average concentration was 0.92±1.25µg in non–vitrectomized eyes. In vitrectomized eyes, average concentration was 1.99±2.35µg at 20 days and the triamcinolone was not detected in five of six eyes at 30 days. The logarithmical plotting shows that the triamcinolone was eliminated 1.84 times quickly in vitrectomized eyes. Conclusions:As a result, the concentration of the IVT decreased at different rates according to vitrectomized or not. We could get the data of the elimination rate in vitrectomized and non–vitrectomized eyes. From the result, we could found out that appropriate interval of reinjection of triamcinolone in vitrectomized eyes is different from non–vitrectomized eyes. It is considered that the right time for second injection was four weeks in non–vitrectomized eyes and two weeks after first trial in case of vitrectomized eyes.
Keywords: pharmacology • injection • vitreous