Abstract
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.
Highlights
Ocular drug delivery is a rapidly expanding pharmaceutical market and a key target area for the pharmaceutical industry
Biomaterials are used in several clinical applications, e.g., joint replacement by metal-based materials [24], heart valves [25], blood vessel prosthesis [26,27], breast implants [28], as well as for drug delivery, such as delivery of subcutaneous contraceptives [29] among others
This change in shape of the fibrils in vitreous humor and PBS suggests that poly(ester amides) (PEAs) fibrils would be useful as drug delivery devices, because drug loaded fibrils could be injected into the vitreous humor where they would remodel, allowing a lower surface to volume ratio (Table 2) decreasing adverse side effects related to implant size
Summary
Ocular drug delivery is a rapidly expanding pharmaceutical market and a key target area for the pharmaceutical industry. To avoid the complications associated with frequent intraocular injections, a sustained-release drug delivery device would be required. A new class of amino acid based poly(ester amide) (PEA) polymers have been developed that meet the requirements of an efficient and useful drug delivery system [16,17,18,19,20]. The ability to encapsulate and release a variety of drug species, including protein drugs, coupled with the lack of side effects of degradation products and versatile processability of the PEA polymers to be manufactured as injectable fibrils and microparticles, makes PEA platform ideal as a vehicle for the prolonged delivery of ophthalmic drugs. The fibrils degrade by surface erosion in presence of proteases which makes them attractive for further research as a potential long-term drug eluting device
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