title: Drug loading optimization and extended drug delivery of corticoids from pHEMA based soft contact lenses hydrogels via chemical and microstructural modifications.
abstract: This paper proposes an approach to improve drug loading capacity and release properties of poly(2-hydroxyethyl methacrylate) (p(HEMA)) soft contact lenses based on the optimization of the hydrogel composition and microstructural modifications using water during the polymerization process. P(HEMA) based soft contact lenses were prepared by thermal or photopolymerization of 2-hydroxyethyl methacrylate (HEMA) solutions containing ethylene glycol di-methacrylate as crosslinker and different proportions of N-vinyl-2-pyrrolidone (NVP) or methacrylic acid (MA) as co-monomers. Transmittance, water uptake, swelling, microstructure, drug absorption isotherms and in vitro release were characterized using triamcinolone acetonide (TA) as model drug. Best drug loading ratios were obtained with lenses containing the highest amount (200 mM) of MA. Incorporation of 40% V/V of water during the polymerization increases the hydrogel porosity giving a better drug loading capacity. In vitro TA release kinetics shows that MA hydrogels released the drug significantly faster than NVP-hydrogels. Drug release was found to be diffusion controlled and kinetics was shown to be reproducible after consecutive drug loading/release processes. Results of p(HEMA) based soft contact lenses copolymerized with ethylene glycol dimethacrylate (EGDMA) and different co-monomers could be a good alternative to optimize the loading and ocular drug delivery of this corticosteroid drug.
authors.affiliation: Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Santiago de Compostela, Campus Vida s/n, 15782 Santiago de Compostela, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: García-Millán
authors.affiliation: Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Santiago de Compostela, Campus Vida s/n, 15782 Santiago de Compostela, Spain.
authors.forename: Sandra
authors.initials: S
authors.lastname: Koprivnik
authors.affiliation: Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Santiago de Compostela, Campus Vida s/n, 15782 Santiago de Compostela, Spain; Instituto de Farmacia Industrial, Facultad de Farmacia, Universidad de Santiago de Compostela, Campus Vida s/n, 15782 Santiago de Compostela, Spain. Electronic address: francisco.otero@usc.es.
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Otero-Espinar
mesh_terms: D000305:Adrenal Cortex Hormones / Q000008:administration & dosage*; D002626:Chemistry, Pharmaceutical; D003263:Contact Lenses, Hydrophilic; D003432:Cross-Linking Reagents; D004339:Drug Compounding; D016503:Drug Delivery Systems; D020100:Hydrogels / Q000737:chemistry*; D007700:Kinetics; D008689:Methacrylates / Q000737:chemistry; D011102:Polyhydroxyethyl Methacrylate / Q000737:chemistry*; D016062:Porosity; D011205:Povidone / Q000737:chemistry; D013816:Thermodynamics; D014222:Triamcinolone Acetonide / Q000008:administration & dosage; D014867:Water
chemical_list: D000305:Adrenal Cortex Hormones; D003432:Cross-Linking Reagents; D020100:Hydrogels; D008689:Methacrylates; D014867:Water; C008384:methacrylic acid; D011102:Polyhydroxyethyl Methacrylate; D014222:Triamcinolone Acetonide; D011205:Povidone
keywords: Controlled drug release/delivery; Hydrogels; Microstructure; Ophthalmic drug delivery; Poly(2-hydroxyethyl methacrylate); Therapeutic soft contact lenses; Triamcinolone acetonide