Controlled release of triamcinolone from an episcleral micro film delivery system for open-globe eye injuries and proliferative vitreoretinopathy.

Open globe trauma is the major cause for single eye blindness that stem from subsequent proliferative vitreoretinopathy (PVR). Though biomaterials and tissue engineering have significantly advanced drug delivery and management of human diseases, currently there is no effective drug formulation or device to pharmacologically mitigate PVR formation after open-globe eye trauma. This highlighted the challenge we are facing to bring the technology from bench to bedside. The current study reported an engineered episcleral drug film using biodegradable material, Poly(L-lactide)-co-poly(ɛ-caprolactone), and triamcinolone acetonide (TA) as a model drug. The film can be conveniently sized into any shape to fit the configuration of the eye globe trauma and easily installed onto the ruptured sclera during primary trauma repair surgery. The film allows therapeutic TA to slow release for at least 6 months without toxicity and demonstrated a significant benefit to reduce the odds of developing severe PVR by 5.7 times when compared with a no-drug film control on a rabbit trauma PVR model. Our results suggested this micro episcleral drug film as promising drug delivery carrier for the targeted treatment of various unwanted retinal proliferation diseases.

Hydrophobic drug adsorption loss to syringe filters from a perspective of drug delivery.

Filtering with a syringe filter is a common operation in pharmaceutical analysis. Ophthalmic research often has a limited amount of sample and low amount of drug which is vulnerable to filtering membrane adsorption loss but not well recognized in the research community. Current study investigated drug adsorption by 11 types of syringe filters for 4 hydrophobic compounds commonly encountered in transscleral drug delivery. Among the 11 types of syringe filters surveyed, polytetrafluoroethylene - NBA, polytetrafluoroethylene - NLA, and polypropylene filters caused the least adsorptive drug loss for these four drugs studied. The magnitude of drug adsorption was filter- and drug-specific. Polytetrafluoroethylene-NLA caused the least adsorptive loss (1%) for triamcinolone acetonide, polytetrafluoroethylene-NBA caused the least adsorptive loss (5.4%) for diclofenac, and polypropylene caused the least adsorptive loss for cyclosporine A, 16.8% on average. Tacrolimus had the least adsorptive loss to the filters of polytetrafluoroethylene - NLA and polypropylene; however, the percentage of adsorptive loss from filtration was the highest (32% loss in average) among the four drugs surveyed. CONCLUSION: Low drug concentrations as seen in samples from ophthalmic researches are vulnerable to filtration drug loss. Selecting the right filter via validation is critical to avoid underestimating the drug level and distorting the resultant distribution/clearance profile in the ocular pharmacokinetic analysis.