title: How cyclodextrin incorporation affects the properties of protein-loaded PLGA-based microspheres: the case of insulin/hydroxypropyl-beta-cyclodextrin system.
abstract: The aim of this work was to study the influence of cyclodextrin (CD) incorporation on the properties of protein-loaded poly(lactide-co-glycolide) (PLGA) microspheres, with particular regards to protein release kinetics. To this purpose, insulin-loaded microspheres were prepared by spray-drying emulsion or solution formulations, with or without hydroxypropyl-beta-cyclodextrin (HPbetaCD), and fully characterized for encapsulation efficiency and release kinetics of both insulin and cyclodextrin. Homogeneous populations of spherical microparticles entrapping both insulin and HPbetaCD were obtained. In order to get an insight into insulin/HPbetaCD interactions occurring inside microspheres, Fourier transform infrared (FTIR) analysis in the Amide I region was performed. FTIR spectra of dried microspheres containing HPbetaCD showed a change in insulin secondary structure, attributed to the presence of insulin/HPbetaCD complexes within microspheres. Insulin release was affected by the presence of HPbetaCD depending on the initial formulation conditions. In the case of microspheres prepared from emulsion, cyclodextrin reduced only insulin burst, whereas in the case of microspheres obtained from solution, the overall insulin release rate was slowed down. Combining the release kinetics of HPbetaCD with the FTIR results on hydrated microspheres, it was concluded that the formation of insulin/HPbetaCD complexes inside microspheres is critical to decrease protein diffusivity in the polymer matrix and achieve an effective modulation of protein release rate.
authors.affiliation: Dipartimento di Chimica Farmaceutica e Tossicologica, Università degli Studi di Napoli Federico II, Via D. Montesano 49, 80131 Napoli, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: De Rosa
authors.forename: Domenico
authors.initials: D
authors.lastname: Larobina
authors.forename: Maria
authors.initials: M
authors.lastname: Immacolata La Rotonda
authors.forename: Pellegrino
authors.initials: P
authors.lastname: Musto
authors.forename: Fabiana
authors.initials: F
authors.lastname: Quaglia
authors.forename: Francesca
authors.initials: F
authors.lastname: Ungaro
mesh_terms: D000073738:2-Hydroxypropyl-beta-cyclodextrin; D000818:Animals; D002417:Cattle; D007328:Insulin / Q000032:analysis / Q000737:chemistry*; D019344:Lactic Acid / Q000032:analysis / Q000737:chemistry*; D008863:Microspheres; D011100:Polyglycolic Acid / Q000032:analysis / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000032:analysis / Q000737:chemistry*; D011506:Proteins / Q000032:analysis / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D047392:beta-Cyclodextrins / Q000032:analysis / Q000737:chemistry*
chemical_list: D007328:Insulin; D011108:Polymers; D011506:Proteins; D047392:beta-Cyclodextrins; D000073738:2-Hydroxypropyl-beta-cyclodextrin; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid