title: Comparative static curing versus dynamic curing on tablet coating structures.
abstract: Curing is generally required to stabilize film coating from aqueous polymer dispersion. This post-coating drying step is traditionally carried out in static conditions, requiring the transfer of solid dosage forms to an oven. But, curing operation performed directly inside the coating equipment stands for an attractive industrial application. Recently, the use of various advanced physico-chemical characterization techniques i.e., X-ray micro-computed tomography, vibrational spectroscopies (near infrared and Raman) and X-ray microdiffraction, allowed new insights into the film-coating structures of dynamically cured tablets. Dynamic curing end-point was efficiently determined after 4h. The aim of the present work was to elucidate the influence of curing conditions on film-coating structures. Results demonstrated that 24h of static curing and 4h of dynamic curing, both performed at 60°C and ambient relative humidity, led to similar coating layers in terms of drug release properties, porosity, water content, structural rearrangement of polymer chains and crystalline distribution. Furthermore, X-ray microdiffraction measurements pointed out different crystalline coating compositions depending on sample storage time. An aging mechanism might have occur during storage, resulting in the crystallization and the upward migration of cetyl alcohol, coupled to the downward migration of crystalline sodium lauryl sulfate within the coating layer. Interestingly, this new study clearly provided further knowledge into film-coating structures after a curing step and confirmed that curing operation could be performed in dynamic conditions.
authors.affiliation: Univ Paris-Sud, EA 4041, Groupe de Chimie Analytique de Paris-Sud, IFR 141-IPSIT, Faculty of Pharmacy, 92296 Châtenay-Malabry, France. claire.gendre@gmail.com
authors.forename: Claire
authors.initials: C
authors.lastname: Gendre
authors.forename: Muriel
authors.initials: M
authors.lastname: Genty
authors.forename: Barbara
authors.initials: B
authors.lastname: Fayard
authors.forename: Ali
authors.initials: A
authors.lastname: Tfayli
authors.forename: Mathieu
authors.initials: M
authors.lastname: Boiret
authors.forename: Olivier
authors.initials: O
authors.lastname: Lecoq
authors.forename: Michel
authors.initials: M
authors.lastname: Baron
authors.forename: Pierre
authors.initials: P
authors.lastname: Chaminade
authors.forename: Jean Manuel
authors.initials: JM
authors.lastname: Péan
mesh_terms: D003460:Crystallization; D004339:Drug Compounding / Q000379:methods*; D005233:Fatty Alcohols / Q000737:chemistry; D006358:Hot Temperature; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D019265:Spectroscopy, Near-Infrared; D013059:Spectrum Analysis, Raman; D013607:Tablets / Q000737:chemistry*; D014961:X-Ray Diffraction; D055114:X-Ray Microtomography
chemical_list: D005233:Fatty Alcohols; D013607:Tablets; D012967:Sodium Dodecyl Sulfate; C005031:cetyl alcohol
keywords: Aqueous ethylcellulose dispersion; Curing; Film-coating structures; Near infrared spectroscopy; X-ray micro-computed tomography; X-ray microdiffraction