Abstract
Delivering an effective drug load to the posterior section of the ocular tissues, while using a non-invasive technique, has always been a challenge. In this regard, the goal of the present study was to develop sustained release triamcinolone acetonide (TA) loaded polymeric matrix films for ocular delivery. The TA-films were prepared in two different polymer matrices, with drug loadings of 10% and 20% w/w, and they were evaluated for ocular distribution in vivo in a conscious rabbit model. A 4% w/v TA suspension (TA-C) was used as a control for in vitro and in vivo studies. The TA-films, prepared with melt-cast technology, used polyethylene oxide (PEO) and Soluplus® as the polymer matrix. The films were evaluated with respect to assay, content uniformity, excipient interaction, and permeability across isolated rabbit sclera. The distribution of TA in the ocular tissues, post topical administration, was determined in New Zealand male albino rabbits as a function of dose, and was compared against TA-C. The assay of the 10% and 20% w/w film was in the range from 70–79% and 92–94% for the Soluplus® and PEO films, respectively, and content uniformity was in the range of 95–103% for both the films. The assay of the TA from Soluplus® films was less compared with the PEO films and showed an interaction with TA, as revealed by Differential Scanning Calorimetry (DSC). Hence, Soluplus® films were not selected for further studies. No interaction was observed between the drug and PEO polymer matrix. The enhancement of trans-scleral flux and permeability of TA was about 1.16 and 1.33-folds, respectively, from the 10% w/w PEO and 3.5 and 2.12-folds, respectively, from the 20% w/w PEO films, as compared with TA-C formulations. The in vivo studies demonstrate that significantly higher TA levels were observed in the anterior and posterior segments of the eye at the end of 6h with the PEO films. Therefore, the PEO based polymeric films were able to deliver TA into the back of the eye efficiently and for prolonged periods.
Highlights
Ophthalmic drug delivery is a challenging task because of the complex physiology and structure of the eye
The melt cast process coverts the drug to its amorphous form, or molecular dispersion state, which in turn increases the solubility of the drug
Triamcinolone acetonide (TA) polymeric films were successfully developed with high drug content and good uniformity and stability
Summary
Ophthalmic drug delivery is a challenging task because of the complex physiology and structure of the eye. Topical ophthalmic drug delivery is the most preferred method in the treatment of the ocular diseases due to their effortless and painless application to the eye. There are many physiological and anatomical restraints, which include tear dilution, nasolacrimal drainage, loss due to blinking, low formulation volume, or low residence time and tissue barriers, such as cornea and conjunctiva, which extensively inhibits the drug permeation [1,2]. The current practice is to administer TA suspension as an intravitreal injection [7,8]. This procedure is associated with side-effects, such as increased ocular pressure, retinal hemorrhage, and endophthalmitis [9,10]
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