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28 October 2019 Tablets & Capsules Figure 1 Surface roughness of tablet cores Surface roughness (microns) 2.5 2 1.5 1 0.5 0 MCC + SSG MCC MCC + MgSt MCC + SSF Easytab MCC + CCS MCC + PVPP the coating was carefully detached at the edge of the tablets using a scalpel. Results Tensile strength. A high tablet tensile strength indi- cates good compaction behavior and is important for withstanding the tablet coating process [1]. However, it is well known that lubricants decrease a tablet's tensile strength [2]. Of the tablet core formulations tested, pure MCC showed the highest tensile strength, while the for- mulation containing MgSt displayed the largest reduction in tensile strength, as shown in Table 2. The coprocessed excipient, which contains SSF, showed a higher tensile strength (hence, better compactibility) than the physical mixture of MCC with SSF. The disintegrants only slightly decreased the ten- sile strength of the tablet cores, and that decrease was nearly the same for CCS, PVPP, and SSG. This can be attributed to the disintegrants' high capacity for forming hydrogen bonds, which are crucial for their disintegra- tion properties and enable strong interactions with the MCC particles. strength and surface roughness of the tablets as well as the film coating adhesion of aqueous HPMC coatings on these tablets were studied. Materials The study used microcrystalline cellulose Vivapur 12 (MCC), sodium stearyl fumarate PRUV (SSF), croscar- mellose sodium Vivasol (CCS), crospovidone Vivapharm PVPP XL (PVPP), sodium starch glycolate Explotab (SSG), Prosolv Easytab SP, and magnesium stearate Ligamed MF-2-V (MgSt) as tablet-core excipients. The tablets were coated with the ready-to-use HPMC coat- ing Vivacoat A. All ingredients came from JRS Pharma, Germany, except for the MgSt, which came from Peter Greven, Germany. Methods Compaction and coating. Seven different tablet core formulations (Table 1) were compacted at a pres- sure of 125 megapascals using a compaction simulator (St yl 'One Evolution, Medel ' Phar m) equipped with bi-planar round punches with a diameter of 11.28 milli- meters. The tablet cores were coated using a perforated drum coater (Solidlab 2, Bosch Hüttlin) with a tablet bed temperature of 38 ± 2°C. Tablet characterization. The tensile strength of the tablets was measured with a hardness tester (MultiT- est 50, Sotax). The surface roughness was measured by profilometr y (DektakXT stylus profiler, Bruker). Scanning electron micrograph (SEM) images of the tablet surfaces were taken using a tabletop microscope (TM-1000, Hitachi) and evaluated in terms of texture, morphology, and quality. Adhesion between the film coating and the tablet surface was measured using a material testing machine (Retroline BZ2, Zwick Roell) by applying double-sided adhesive tape to fix the tab- let to even punches. Prior to adhesion measurement, Formulation Lubricant Disintegrant MCC MCC - - 100% MCC + MgSt 1% MgSt - 99% MCC + SSF 1% SSF - 99% MCC + CCS - 5% CCS 95% MCC + PVPP - 5% PVPP 95% MCC + SSG - 5% SSG 95% Prosolv Easytab SSF SSG SMCC Table 1 Excipient composition of the investigated tablet cores Formulation Tensile strength (megapascals) MCC 6.62 MCC + MgSt 1.16 MCC + SSF 3.27 Prosolv Easytab 4.90 MCC + CCS 6.08 MCC + PVPP 5.98 MCC + SSG 5.80 Table 2 Tensile strength of tablet cores (125 megapascals compaction pressure)