(586ag) Evaluation of Film Coated Tablet Surface Roughness Via a Latent Variable Design-of-Experiments (DOE)

Authors: 
Miesle, J. E., Eli Lilly and Company
Manley, L., Eli Lilly & Co.



A one-third fractional factorial design of experiments (DOE) was created utilizing latent variables for two separate spray bars in order to evaluate the impact of those parameters on coated tablet appearance. The variables evaluated were environmental equivalency factor (EEF), spray droplet size and coating pan exhaust temperature while utilizing either a Thomas Engineering Spectrum spray bar or a Spraying Systems VMAU spray bar in a 24” Thomas CompuLab coating pan.  EEF values were calculated using the Thomas Engineering TAAC program.  Droplet sizes were calculated by using an empirical model developed internally from data collected during characterization trials at Spraying Systems, Inc.

Placebo tablets (10 mm round standard concave, debossed on one face) were coated per the DOE conditions and then evaluated for gloss readings and surface roughness.  Gloss readings were measured by Colorcon and represent the amount of light reflected by the tablet.  Surface roughness was measured by non-contact three dimensional (3D) profilometry via a Keyence VK-X100 3D laser scanning microscope.  Roughness measurements were recorded on both faces of five tablets from each DOE run.  Data filtering and smoothing algorithms were applied to each measurement through the use of a template and results were tabulated.  Coated tablet surface roughness values were found to be highly correlated with the Sauter mean droplet diameter (D[3,2]) and to a lesser extent with EEF.

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