Monitoring tablet surface roughness during the film coating process
The purpose of this study was to evaluate the change of surface roughness; the development of the film during the film coating process using laser profilometer roughness measurements, SEM imaging,; energy dispersive X-ray (EDX) analysis. Surface roughness; texture changes developing during the process of film coating tablets were studied by noncontact laser profilometry; scanning electron microscopy (SEM). An EDX analysis was used to monitor the magnesium stearate; titanium dioxide of the tablets. The tablet cores were film coated with aqueous hydroxypropyl methylcellulose,; 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,; 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.
Paulus Seitavuopio1Email:paulus.seitavuopio@helsinki.fi?Jyrki Hein?m?ki1?Jukka Rantanen2?Jouko Yliruusi1
[1] Faculty of Pharmacy, Division of Pharmaceutical Technology, University of Helsinki, PO Box 56, 00014 Helsinki, Finland ;[2] Drug Discovery Technology Center, University of Helsinki, PO Box 56, 00014 Helsinki, Finland
