Synthesis and physicochemical evaluation of novel smart polymer for ocular drug delivery of anti-inflammatory drugs.

The purpose of this study was synthesis of a novel smart copolymer and evaluation of its physicochemical characteristics as a suitable nano-carrier for ophthalmic drug delivery of anti-inflammatory drugs. Polymeric micelles were prepared by free radical copolymerization of N- isopropylacrylamide (NIPAAM), vinyl pyrrolidone (VP), and acrylic acid (AA) as [Poly (NIPAAM-AA-VP)] copolymer and Nisopropylacrylamide-acrylic acid-hydroxyethyl methacrylate as [Poly (NIPAAM-AA-HEM)] in 1, 4-dioxane under N2 atmosphere. In this study triethyleneglycol dimethacrylate (TEGDMA) applied as cross-linking agents. The chemical structures of cross-linked copolymers were confirmed by FT-IR and 1H- NMR spectroscopies. The PSA data represented that the particles had mean size under 500nm. The maximum swelling ratio of hydrogel occurred at 10 min at 37°C and pH 1.0 and at 125 min at 20 °C and pH 1.0. For all formulations, release rate had direct relationship with drug-polymer ratios. In this study dexamethasone and indomethacin was loaded as two model anti-inflammatory medicines in copolymeric structures. The prepared nanoparticles were stable in an aqueous solution and maintained their physicochemical characteristics such as particle size and drug loading content during seven days of storage. Evaluation of physicochemical properties of novel polymeric system showed this system not only was suitable for ocular drug delivery but also could be used as a delayed release system for longer duration of anti-inflammatory effect.