title: Quantitative surface topography assessment of directly compressed and roller compacted tablet cores using photometric stereo image analysis.
abstract: Surface topography, in the context of surface smoothness/roughness, was investigated by the use of an image analysis technique, MultiRay™, related to photometric stereo, on different tablet batches manufactured either by direct compression or roller compaction. In the present study, oblique illumination of the tablet (darkfield) was considered and the area of cracks and pores in the surface was used as a measure of tablet surface topography; the higher a value, the rougher the surface. The investigations demonstrated a high precision of the proposed technique, which was able to rapidly (within milliseconds) and quantitatively measure the obtained surface topography of the produced tablets. Compaction history, in the form of applied roll force and tablet punch pressure, was also reflected in the measured smoothness of the tablet surfaces. Generally it was found that a higher degree of plastic deformation of the microcrystalline cellulose resulted in a smoother tablet surface. This altogether demonstrated that the technique provides the pharmaceutical developer with a reliable, quantitative response parameter for visual appearance of solid dosage forms, which may be used for process and ultimately product optimization.
authors.affiliation: H. Lundbeck A/S, Biologics and Pharmaceutical Science, Ottiliavej 9, DK-2500, Valby, Denmark. Electronic address: MnAq@nnepharmaplan.com.
authors.forename: Morten
authors.initials: M
authors.lastname: Allesø
authors.affiliation: H. Lundbeck A/S, Biologics and Pharmaceutical Science, Ottiliavej 9, DK-2500, Valby, Denmark.
authors.forename: Per
authors.initials: P
authors.lastname: Holm
authors.affiliation: Technical University of Denmark, DTU Compute, Department of Applied Mathematics and Computer Science, Richard Petersens Plads, Building 321, room 216, DK-2700 Lyngby, Denmark; Videometer A/S, Lyngsø Allé 3, DK-2970 Hørsholm, Denmark.
authors.forename: Jens Michael
authors.initials: JM
authors.lastname: Carstensen
authors.affiliation: H. Lundbeck A/S, Biologics and Pharmaceutical Science, Ottiliavej 9, DK-2500, Valby, Denmark.
authors.forename: René
authors.initials: R
authors.lastname: Holm
mesh_terms: D002266:Carboxymethylcellulose Sodium / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D010783:Photometry / Q000379:methods*; D011312:Pressure; D015203:Reproducibility of Results; D013499:Surface Properties; D013607:Tablets / Q000737:chemistry*; D013678:Technology, Pharmaceutical / Q000379:methods*
chemical_list: D013607:Tablets; D002482:Cellulose; D002266:Carboxymethylcellulose Sodium; C109691:microcrystalline cellulose
keywords: Microcrystalline cellulose; MultiRay™ image analysis; Powder compaction; Roller compaction; Surface roughness; Surface topography; Tablets