Abstract
Purpose: :
Preservative free triamcinolone acetonide (Triescence) has high cost and not readily available in many developing countries. The current study aims to compare commercially available three preparations of triamcinolone to Triescence in the prospect of intravitreal application.
Methods: :
The osmolarity, crystallinity and particle sizes of Triescence, Kenalog-40, Jida China and Tongyong China were tested and the solubility was determined at 37°C in physiologic ironic strength in vitro experiments.In the in vivo study 1.2 mg of each TA preparation was injected into the rabbit vitreous and vitreous free TA concentration was determined by HPLC. The in vivo safety was evaluated in guinea pig eyes through intravitreal injection proportionally to clinical human intravitreal dosage by biomicroscopy, electrophysiology and histology.
Results: :
The solubility of TA at 37°C in PBS (ironic strength=0.2M) was 13.42, 12.91, 12.51 and 1.96µg/ml for Triescence, kenalog-40, Jida China and Tongyong China respectively. The osmolarity was 300.7±2.1, 328.7±1.7, 309.3±1.9 and 269.7±4.1 mOsm/kg. The crystallinity determined by XRD was 100%, 100%, 88.79% and 88.86%. The average particle size is 11.51µm, 18.66µm, 10.13µm and 6.69µm. The vitreous free TA concentration was 21.63±1.92 µg/ml for Triescence, 19.69±0.21 µg/ml for Kenalog-40, 21.14±0.82 µg/ml for Jida China and 35.52 µg/ml for Tongyong China (triamcinolone acetonide acetate). The in vivo safety study did not reveal any retinal toxicity from four types of triamcinolone preparation.
Conclusions: :
The four types of commercial triamcinolone seemed to be safe if 4mg in 0.1ml or lower doses is used for human intravitreal injection. The pharmacokinetic differences among those TA preparations need to be further investigated.
Keywords: corticosteroids • vitreous • injection