Safety and efficacy of intracapsular tranilast microspheres in experimental posterior capsule opacification.
ABSTRACT To evaluate the safety and efficacy of a sustained-release agent designed to reduce posterior capsule opacification (PCO).
Department of Ophthalmology, EENT Hospital, Fudan University, Shanghai, Peoples Republic of China.
Free tranilast (TFree) was incorporated into polylactic acid microspheres and then tested using a rabbit model of PCO. Twenty-nine rabbits were randomized into 5 groups treated with balanced saline solution (BSS control); TFree; or 0.5, 1.0, or 2.0 mg tranilast microspheres (TMicro). Standard phacoemulsification cataract surgery, including manual aspiration of all visible soft lens matter, was performed in all groups. The selected test agent was then injected into the lens capsule. Postoperative clinical examinations were performed at 1, 3, 7, 14, 30, 60, and 90 days. Posterior capsule opacification was quantified using high-resolution computer image analysis at 1, 2, and 3 months. Histological examination was performed at 3 months.
Eyes treated with TMicro had significantly less PCO than the eyes in the BSS and TFree groups. While the BSS control eyes had increased PCO over 3 months, eyes in the TMicro group had reduced PCO over time in a dose-dependent fashion. Histological examination showed reduced lens epithelial cell proliferation in the TMicro groups, with no manifest damage to the cornea, iris, or retina compared with the BSS controls. There was a transient increase in postoperative inflammation in all tranilast-treated groups compared with the BSS controls.
Sustained-release intracapsular tranilast reduced PCO in an experimental model of PCO, suggesting further investigation of its therapeutic potential is justified.
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ABSTRACT: Eye-drops are the conventional dosage forms that account for 90% of currently accessible ophthalmic formulations. Despite the excellent acceptance by patients, one of the major problems encountered is rapid precorneal drug loss. To improve ocular drug bioavailability, there is a significant effort directed towards new drug delivery systems for ophthalmic administration. This chapter will focus on three representative areas of ophthalmic drug delivery systems: polymeric gels, colloidal systems, cyclodextrins and collagen shields. Hydrogels generally offer a moderate improvement of ocular drug bioavailability with the disadvantage of blurring of vision. In situ activated gel-forming systems are preferred as they can be delivered in drop form with sustained release properties. Colloidal systems including liposomes and nanoparticles have the convenience of a drop, which is able to maintain drug activity at its site of action and is suitable for poorly water-soluble drugs. Among the new therapeutic approaches in ophthalmology, cyclodextrins represent an alternative approach to increase the solubility of the drug in solution and to increase corneal permeability. Finally, collagen shields have been developed as a new continuous-delivery system for drugs that provide high and sustained levels of drugs to the cornea, despite a problem of tolerance. It seems that new tendency of research in ophthalmic drug delivery systems is directed towards a combination of several drug delivery technologies. There is a tendency to develop systems which not only prolong the contact time of the vehicle at the ocular surface, but which at the same time slow down the elimination of the drug. Combination of drug delivery systems could open a new directive for improving results and the therapeutic response of non-efficacious systems.Progress in Retinal and Eye Research 01/1998; 17(1):33-58. · 9.44 Impact Factor
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