title: Investigating the effect of tablet thickness and punch curvature on density distribution using finite elements method.
abstract: Finite elements method was used to study the influence of tablet thickness and punch curvature on the density distribution inside convex faced (CF) tablets. The modeling of the process was conducted on 2 pharmaceutical excipients (anhydrous calcium phosphate and microcrystalline cellulose) by using Drucker-Prager Cap model in Abaqus(®) software. The parameters of the model were obtained from experimental tests. Several punch shapes based on industrial standards were used. A flat-faced (FF) punch and 3 convex faced (CF) punches (8R11, 8R8 and 8R6) with a diameter of 8mm were chosen. Different tablet thicknesses were studied at a constant compression force. The simulation of the compaction of CF tablets with increasing thicknesses showed an important change on the density distribution inside the tablet. For smaller thicknesses, low density zones are located toward the center. The density is not uniform inside CF tablets and the center of the 2 faces appears with low density whereas the distribution inside FF tablets is almost independent of the tablet thickness. These results showed that FF and CF tablets, even obtained at the same compression force, do not have the same density at the center of the compact. As a consequence differences in tensile strength, as measured by diametral compression, are expected. This was confirmed by experimental tests.
authors.affiliation: Institut de Mécanique et d'Ingénierie (I2 M, CNRS UMR 5295), Université de Bordeaux, 146 rue Léo Saignat (case 15), Laboratoire de pharmacie galénique et biopharmacie, Bâtiment pharmacie 1(ère) tranche, 3(ème) étage, F-33076 Bordeaux cedex, France; Université Paris Sud, 5 rue Jean-Baptiste Clément, 92296 Châtenay-Malabry, France. Electronic address: harona.diarra@u-psud.fr.
authors.forename: Harona
authors.initials: H
authors.lastname: Diarra
authors.affiliation: Institut de Mécanique et d'Ingénierie (I2 M, CNRS UMR 5295), Université de Bordeaux, 146 rue Léo Saignat (case 15), Laboratoire de pharmacie galénique et biopharmacie, Bâtiment pharmacie 1(ère) tranche, 3(ème) étage, F-33076 Bordeaux cedex, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Mazel
authors.affiliation: Institut de Mécanique et d'Ingénierie (I2 M, CNRS UMR 5295), Université de Bordeaux, 146 rue Léo Saignat (case 15), Laboratoire de pharmacie galénique et biopharmacie, Bâtiment pharmacie 1(ère) tranche, 3(ème) étage, F-33076 Bordeaux cedex, France; Université Paris Sud, 5 rue Jean-Baptiste Clément, 92296 Châtenay-Malabry, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Busignies
authors.affiliation: Institut de Mécanique et d'Ingénierie (I2 M, CNRS UMR 5295), Université de Bordeaux, 146 rue Léo Saignat (case 15), Laboratoire de pharmacie galénique et biopharmacie, Bâtiment pharmacie 1(ère) tranche, 3(ème) étage, F-33076 Bordeaux cedex, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Tchoreloff
mesh_terms: D002130:Calcium Phosphates / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry*; D003198:Computer Simulation; D005079:Excipients / Q000737:chemistry*; D020342:Finite Element Analysis; D011208:Powders / Q000737:chemistry; D011312:Pressure; D013314:Stress, Mechanical; D013607:Tablets / Q000737:chemistry*; D013678:Technology, Pharmaceutical; D013718:Tensile Strength
chemical_list: D002130:Calcium Phosphates; D005079:Excipients; D011208:Powders; D013607:Tablets; D002482:Cellulose; C020243:calcium phosphate; C109691:microcrystalline cellulose
keywords: Convex faced tablet; Density distribution; Die compression; FEM simulation