title: Ethanol-resistant ethylcellulose/guar gum coatings--importance of formulation parameters.
abstract: Recently, ethylcellulose/guar gum blends have been reported to provide ethanol-resistant drug release kinetics from coated dosage forms. This is because the ethanol insoluble guar gum effectively avoids undesired ethylcellulose dissolution in ethanol-rich bulk fluids. However, so far the importance of crucial formulation parameters, including the minimum amount of guar gum to be incorporated and the minimum required guar gum viscosity, remains unclear. The aim of this study was to identify the most important film coating properties, determining whether or not the resulting drug release kinetics is ethanol-resistant. Theophylline matrix cores were coated in a fluid bed with blends of the aqueous ethylcellulose dispersion "Aquacoat®ECD30" and guar gum. The polymer blend ratio, guar gum viscosity, and degree of dilution of the final coating dispersion were varied. Importantly, it was found that more than 5% guar gum (referred to the total polymer content) must be incorporated in the film coating and that the apparent viscosity of a 1% aqueous guar gum solution must be greater than 150 cP to provide ethanol-resistance. In contrast, the investigated degree of coating dispersion dilution was not found to be decisive for the ethanol sensitivity. Furthermore, all investigated formulations were long term stable, even upon open storage under stress conditions for 6 months.
authors.affiliation: Univ. Lille Nord de France, College of Pharmacy, Lille, France; INSERM U 1008, Controlled Drug Delivery Systems and Biomaterials, Lille, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Rosiaux
authors.forename: C
authors.initials: C
authors.lastname: Velghe
authors.forename: S
authors.initials: S
authors.lastname: Muschert
authors.forename: R
authors.initials: R
authors.lastname: Chokshi
authors.forename: B
authors.initials: B
authors.lastname: Leclercq
authors.forename: F
authors.initials: F
authors.lastname: Siepmann
authors.forename: J
authors.initials: J
authors.lastname: Siepmann
mesh_terms: D000428:Alcohol Drinking; D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D003692:Delayed-Action Preparations; D004355:Drug Stability; D000431:Ethanol / Q000737:chemistry*; D005079:Excipients; D005685:Galactans / Q000737:chemistry*; D007700:Kinetics; D008351:Mannans / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D053149:Plant Gums / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D012995:Solubility; D012996:Solutions; D013499:Surface Properties; D013806:Theophylline / Q000737:chemistry; D014783:Viscosity
chemical_list: D003692:Delayed-Action Preparations; D005079:Excipients; D005685:Galactans; D008351:Mannans; D053149:Plant Gums; D011108:Polymers; D012996:Solutions; D000431:Ethanol; C013517:ethyl cellulose; D002482:Cellulose; D013806:Theophylline; C007894:guar gum
keywords: Controlled release; Ethanol-resistance; Ethylcellulose; Film coating; Guar gum; Pellets