title: Nanocapsules prepared from amorphous polyesters: effect on the physicochemical characteristics, drug release, and photostability.
abstract: The influence of the polymeric amorphous materials on the physicochemical and drug release properties of drug-loaded nanocapsules as well as their role on the protection of the entrapped drug against the degradation induced by UV radiation was evaluated. Nanocapsules were prepared by interfacial deposition of preformed polymer (PLA, PLGA 50:50, and PLGA 85:15) using clobetasol propionate as the drug model. In vitro drug release was evaluated by the dialysis bag method. Photochemical stability was studied under UVA radiation. After preparation, all formulations presented nanometric mean size (180-200 nm), polydispersity index below 0.20, acid pH, negative zeta potential, and encapsulation efficiency close to 100%. Clobetasol propionate-loaded PLGA nanocapsules presented a lower physicochemical stability, showing a high drug leakage during 3 months of storage. In vitro studies showed biphasic drug release from all nanocapsules (according to an anomalous transport) and no influence of the hydrophilic characteristics of the amorphous polymeric material on the release rate. The photostability of clobetasol propionate under UVA radiation was improved by its incorporation into PLA and PLGA nanocapsules showing that besides semicrystalline polymers, amorphous polymers could also efficiently protect nanoencapsulated drugs against UV radiation.
authors.affiliation: Programa de Pós-Graduação em Ciências Farmacêuticas, Centro de Ciências da Saúde, Departamento de Farmácia Industrial, Av. Roraima, 1000, Universidade Federal de Santa Maria, Santa Maria, RS 97105-900, Brazil.
authors.forename: M C
authors.initials: MC
authors.lastname: Fontana
authors.forename: K
authors.initials: K
authors.lastname: Coradini
authors.forename: A R
authors.initials: AR
authors.lastname: Pohlmann
authors.forename: S S
authors.initials: SS
authors.lastname: Guterres
authors.forename: R C R
authors.initials: RC
authors.lastname: Beck
mesh_terms: D000042:Absorption; D002990:Clobetasol / Q000008:administration & dosage / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D004058:Diffusion; D004337:Drug Carriers / Q000737:chemistry* / Q000528:radiation effects; D004355:Drug Stability; D008027:Light; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D053769:Nanocapsules / Q000737:chemistry* / Q000648:ultrastructure*; D050997:Nanomedicine / Q000379:methods*; D010316:Particle Size; D044367:Phase Transition; D011091:Polyesters / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D004337:Drug Carriers; D046911:Macromolecular Substances; D053769:Nanocapsules; D011091:Polyesters; D002990:Clobetasol