title: Monitoring tablet surface roughness during the film coating process.
abstract: The purpose of this study was to evaluate the change of surface roughness and the development of the film during the film coating process using laser profilometer roughness measurements, SEM imaging, and energy dispersive X-ray (EDX) analysis. Surface roughness and texture changes developing during the process of film coating tablets were studied by noncontact laser profilometry and scanning electron microscopy (SEM). An EDX analysis was used to monitor the magnesium stearate and titanium dioxide of the tablets. The tablet cores were film coated with aqueous hydroxypropyl methylcellulose, and the film coating was performed using an instrumented pilot-scale side-vented drum coater. The SEM images of the film-coated tablets showed that within the first 30 minutes, the surface of the tablet cores was completely covered with a thin film. The magnesium signal that was monitored by SEM-EDX disappeared after ~15 to 30 minutes, indicating that the tablet surface was homogeneously covered with film coating. The surface roughness started to increase from the beginning of the coating process, and the increase in the roughness broke off after 30 minutes of spraying. The results clearly showed that the surface roughness of the tablets increased until the film coating covered the whole surface area of the tablets, corresponding to a coating time period of 15 to 30 minutes (from the beginning of the spraying phase). Thereafter, the film only became thicker. The methods used in this study were applicable in the visualization of the changes caused by the film coating on the tablet surfaces.
authors.affiliation: Faculty of Pharmacy, Division of Pharmaceutical Technology, University of Helsinki, PO Box 56, 00014 University of Helsinki, Finland. paulus.seitavuopio@helsinki.fi
authors.forename: Paulus
authors.initials: P
authors.lastname: Seitavuopio
authors.forename: Jyrki
authors.initials: J
authors.lastname: Heinämäki
authors.forename: Jukka
authors.initials: J
authors.lastname: Rantanen
authors.forename: Jouko
authors.initials: J
authors.lastname: Yliruusi
mesh_terms: D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D004339:Drug Compounding / Q000379:methods*; D065347:Hypromellose Derivatives; D008422:Materials Testing; D008567:Membranes, Artificial; D008747:Methylcellulose / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D013229:Stearic Acids / Q000032:analysis*; D013499:Surface Properties; D013607:Tablets / Q000032:analysis / Q000737:chemistry*; D014025:Titanium / Q000032:analysis*
chemical_list: D020099:Coated Materials, Biocompatible; D008567:Membranes, Artificial; D013229:Stearic Acids; D013607:Tablets; C009495:titanium dioxide; D065347:Hypromellose Derivatives; C031183:stearic acid; D008747:Methylcellulose; D014025:Titanium