title: Rheological Characterization of Ethylcellulose-Based Melts for Pharmaceutical Applications.
abstract: Rheological characterization of ethylcellulose (EC)-based melts intended for the production, via micro-injection moulding (μIM), of oral capsular devices for prolonged release was carried out. Neat EC, plasticized EC and plasticized EC containing solid particles of a release modifier (filler volume content in the melt around 30%) were examined by capillary and rotational rheometry tests. Two release modifiers, differing in both chemical nature and particle geometry, were investigated. When studied by capillary rheometry, neat EC appeared at process temperatures as a highly viscous melt with a shear-thinning characteristic that progressively diminished as the apparent shear rate increased. Thus, EC as such could not successfully be processed via μIM. Plasticization, which induces changes in the material microstructure, enhanced the shear-thinning characteristic of the melt and reduced considerably its elastic properties. Marked wall slip effects were noticed in the capillary flow of the plasticized EC-based melts, with or without release modifier particles. The presence of these particles brought about an increase in viscosity, clearly highlighted by the dynamic experiments at the rotational rheometer. However, it did not impair the material processability. The thermal and rheological study undertaken would turn out a valid guideline for the development of polymeric materials based on pharma-grade polymers with potential for new pharmaceutical applications of μIM.
authors.affiliation: Dipartimento di Ingegneria Meccanica e Industriale, Università degli Studi di Brescia, Brescia, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Baldi
authors.affiliation: Dipartimento di Ingegneria Meccanica e Industriale, Università degli Studi di Brescia, Brescia, Italy.
authors.forename: Juri
authors.initials: J
authors.lastname: Ragnoli
authors.affiliation: Dipartimento di Ingegneria Meccanica e Industriale, Università degli Studi di Brescia, Brescia, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Zinesi
authors.affiliation: Dipartimento di Ingegneria Meccanica e Industriale, Università degli Studi di Brescia, Brescia, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Bignotti
authors.affiliation: Dipartimento di Chimica, Materiali e Ingegneria Chimica "G. Natta", Politecnico di Milano, Milano, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Briatico-Vangosa
authors.affiliation: Dipartimento di Scienze Farmaceutiche, Sezione di Tecnologia e Legislazione Farmaceutiche "Maria Edvige Sangalli", Università degli Studi di Milano, Via G. Colombo 71, I-20133, Milano, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Casati
authors.affiliation: Dipartimento di Scienze Farmaceutiche, Sezione di Tecnologia e Legislazione Farmaceutiche "Maria Edvige Sangalli", Università degli Studi di Milano, Via G. Colombo 71, I-20133, Milano, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Loreti
authors.affiliation: Dipartimento di Scienze Farmaceutiche, Sezione di Tecnologia e Legislazione Farmaceutiche "Maria Edvige Sangalli", Università degli Studi di Milano, Via G. Colombo 71, I-20133, Milano, Italy.
authors.forename: Alice
authors.initials: A
authors.lastname: Melocchi
authors.affiliation: Dipartimento di Scienze Farmaceutiche, Sezione di Tecnologia e Legislazione Farmaceutiche "Maria Edvige Sangalli", Università degli Studi di Milano, Via G. Colombo 71, I-20133, Milano, Italy. lucia.zema@unimi.it.
authors.forename: Lucia
authors.initials: L
authors.lastname: Zema
mesh_terms: D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D005079:Excipients / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D012212:Rheology; D013696:Temperature; D014783:Viscosity
chemical_list: D005079:Excipients; D011108:Polymers; C013517:ethyl cellulose; D002482:Cellulose
keywords: ethylcellulose; micro-injection moulding; prolonged release; rheology