Polyesteramidfibrillen als intraokulare Medikamententräger

In this study „ Polyesteramid fibrils as intraocular drug devices“ we examined the biomaterial polyesteramids as intraocular devices for long term drug delivery. The study was performed in cooperation with DSM Biomedicals, which produced the biomaterials and carried out in vitro analysis as well. The degradation processes were analysed in vitro and the biocompatibilty was analysed in vivo on the basis of rabbit testing. As polyesteramides are degrading through enzymatic processes and enzymatic concentration in pathologic alterated vitreous is elevated, biocompatibility was additionally examined through a disease model, which was induced through vascular leakage by intravitreous injection of vascular endothelial growth factor (VEGF 165). The biomaterial Polylactid-co-glycolic acid (PLGA), which already has a widespread application in medicine, for instance as suture material was examined for checking purposes. The rabbits were evaluated regularly by funduscopic control over a time period of min. 4 weeks and max. 36 weeks, after the polymers have been implanted with 4 mm lenght. Increasement of intraocular pressure was determined by a tonometer. A subgroup of rabbits was evaluated with electroretinographie (ERG) and optic coherence tomography (OCT). At the end of the evaluation period the animals were euthanised and polymers have been explanted for further analysis. The eyeballs were further explored histological and microscopically analysed. Our findings showed an excellent in vivo biocompatibility for polyesteramides, as well as reference to a good regulation of degradation procedure in vitro and in vivo. Furthermore the study has shown, that polyesteramides are a promising carrier material for potential intraocular drug devices. These results are an important approach for further examinations, in which polyesteramides could be equipped with drugs

Biocompatibility of Poly(ester amide) (PEA) Microfibrils in Ocular Tissues

Drug delivery systems (DDS) are able to deliver, over long periods of time, therapeutic concentrations of drugs requiring frequent administration. Two classes of DDS are available, biodegradable and non-biodegradable. The larger non-biodegradable implants ensure long-term delivery, but require surgical interventions. Biodegradable biomaterials are smaller, injectable implants, but degrade hydrolytically and release drugs in non-zero order kinetics, which is inefficient for long-term sustained drug release. Biodegradable poly(ester amides) (PEAs) may overcome these difficulties. To assess their ocular biocompatibility and long-term behavior, PEA fibrils were analyzed in vitro and in vivo. In vitro, incubation in vitreous humor changes to PEA structure, suggests degradation by surface erosion, enabling drug release with zero order kinetics. Clinical and histological analysis of PEA fibrils implanted subconjunctivally and intravitreally showed the absence of an inflammatory response or other pathological tissue alteration. This study shows that PEA fibrils are biocompatible with ocular environment and degrade by surface erosion