Abstract
The aim of this study was to synthesize and characterize the biodegradable intraocular implants based on poly (D,L-lactide-co-glycolide) (PLGA 75:25) with Cyclosporine-A (CyA) and to evaluate their in vitro drug delivery profile. Thermal analysis was conducted by using Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC). Phase analysis and crystallinity of the polymer-CyA samples were assessed through X ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Finally, microstructure and morphology of the systems were investigated by Scanning Electron Microscopy (SEM). The results showed that CyA was successfully incorporated into PLGA network with drug loading of approximately 31.6%. Also, based on FTIR and thermal analyses (TGA/DSC) no significant physical-chemical interaction was detected at the micro-nanoscale level between polymer/drug. SEM micrographs have indicated a uniform drug distribution in PLGA matrix. XRD patterns have showed that the incorporated semi-crystalline structure of CyA has not significantly altered the polymeric mainly amorphous network. In addition, the results have confirmed the chemical and biological drug stability, the drug distribution into the polymeric matrix and the possibility of cyclosporine prolonged delivery system profile.
Highlights
Biodegradable polymers have been largely used in pharmaceuticals and biomedical field, respectively as delivery systems or as biomaterials[1]
The intraocular implants were prepared by molding a lyophilized mixture consisted of a homogeneous mass containing 75% of poly(D,L-lactide-co-glycolide, in ratio of 75:25, called PLGA 75:25) and 25% of cyclosporine A (CyA) into rods using a Teflon® sheet heated on a hot plate at a temperature from 100 to 120 °C
The average weight of implants was 5.9 ± 0.1 mg (n = 10) and the average incorporation of CyA into the polymeric matrix was of 31.6% (n = 3)
Summary
Biodegradable polymers have been largely used in pharmaceuticals and biomedical field, respectively as delivery systems or as biomaterials[1]. The poly (D,L-lactide-co-glycolide) is a classic example amongst the synthetic polymers and has been well applied as drug delivery system due to its satisfactory biocompatibility and absence of significant toxicity in vivo studies[2,3]. The polymer proportion and the chain size will define the in vitro and in vivo copolymer degradation. Besides that, this copolymer presents an amorphous state and its glass transition temperature occurs at, approximately 50 °C. This copolymer presents an amorphous state and its glass transition temperature occurs at, approximately 50 °C This material presents thermoplastic property where copolymer chains are held together by relatively weak van der Waals and dipole-dipole forces[1]
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