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R.C. Oliveira, R. Jorge, R.C. Siqueira, R.A. Costa, J.A. Cardillo, A.A. S. Junior, B. Wanczinski, A.G. Oliveira; Triamcinolone Pellets Obtained by Direct Compression for Intravitreous Drug Delivery . Invest. Ophthalmol. Vis. Sci. 2005;46(13):488.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate the in vitro and in vivo triancinolone release from biodegradable plellets–based triancinolone–load obtained by direct compression of PLGA co–polymer of lactic–co–glicolic acid and triamcinolone. Methods: Triamcinolone–loaded pellets were prepared by direct compression using a matrix with 1 mm of diameter. Theoretical drug loaded in the pellets was 0.85mg. The obtained matrix system was characterized by optical and electronic microscopy. The amounts of the triamcinolone loaded in the pellets were carried out by PHLC. The in vitro release of drug was carried out by incubation of pellets in phosphate buffer pH 7.4 at 37oC and the determination of the dissolved TR by HPLC. Free TR was used as a control. For in vivo experiments the pellets were implanted intravitreous, after sclerotomy, of the rabbit’s right eye. At the appropriated time the animals were sacrificed and vitreous humors were collected and freeze for posterior analysis .The concentrations of the released TR were determined by HPLC. Results: The encapsulation efficiency of triancinolone was about 90% in relation of the theoretical loading of 0.85mg. The analytical TR concentration was determined as 0.75mg per pellet. The size of the pellets were 1mm diameter x 1.8mm length and 1.67mg + 0.136 mg weight. The in vitro TR release was followed for 8 weeks. The in vitro results showed a sigmoidal profile with slow release in the initial times increasing subsequently. For the in vivo release the TR dissolved in the vitreous humor increased reaching a maximum in the first week following by a decrease at least 8 weeks. The decrease in the TR concentration above the first week followed a first order kinetics within the experimental 8 weeks. The accumulative TR released in the in vitro experiment can explain the intravitreal concentrations of the drug in the in vivo experiments. Conclusions: The release of triamcinolone from the pellets in a time–controlled kinetics over several weeks demonstrated the potential of the system for treatment of the diseases of posterior segment of eye.
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