Abstract
Purpose: :
To evaluate the safety and efficacy of a new formulation of micronized injectable triamcinolone in an animal model.
Methods: :
24 pigmented rabbits have been intravitreally injected with 0.1ml (1mg) of a new formulation of micronized triamcinolone (MT). Small particles have dispersed in Carbopol 980 polymer (CP) and saline. One eye of each animal received MT and the fellow eye was injected either with CP only or with standard triamcinolone acentonide (TA) (0.1ml, 4 mg). Anterior segment evaluation, indirect opthalmoscopy was performed daily for the first week, and once a week for the following time. Animals have been sacrificed and enucleated 1 week, 1 month, 2 months and 4 months after injection. The amount of drug in aqueous, vitreous and other ocular tissues have been assessed with HPLC.
Results: :
No animals showed reaction to the substances that have been injected, MT particularly demonstrated good tolerance without appreciable signs of inflammation. MT was macroscopically visible even 2 months after injection, even though TA shows persistence up to the 4 month evaluation. Samples collected at the end of the study reveal that concentration of MT is still significant (12microgr/L ) even if TA show higher values (30microgr/L)
Conclusions: :
Intravitreal injection of triamcinolone is a diffuse and new treatment strategy for otherwise untreatable macular edema or choroidal neovascularization. However, it is considered an off–label use of a drug which has potential risks (toxic effects related to benzylic solvent) and side effects (increased IOP and cataract). MT may represent a valuable alternative for an injectable solution of triamcinolone which can overcome some limitations of the standard preparation.
Keywords: drug toxicity/drug effects • retinal neovascularization