Anisotropic porous structure of pharmaceutical compacts evaluated by PGSTE-NMR in relation to mechanical property anisotropy.
OBJECTIVE
The pore space anisotropy of pharmaceutical compacts was evaluated in relation to the mechanical property anisotropy.


METHODS
The topology and the pore space anisotropy were characterized by PGSTE-NMR measurements. Parallelepipedical compacts of anhydrous calcium phosphate (aCP) and microcrystalline cellulose (MCC) were tested on top, bottom and side faces. A microindentation and three-point single beam tests were used to measure Brinell hardness, tensile strength and Young's modulus. All the data were submitted to a statistical analysis to test for significance.


RESULTS
The porous structure of MCC compacts was anisotropic, contrary to those of aCP. The analysis of the pore space by PGSTE-NMR method showed that its structural anisotropy was controlled by the behaviour under compaction of the excipients. At the same time, the Young's modulus and the tensile strength were the same whatever the direction of testing. For the aCP compacts, all the faces had the same Brinell hardness. With MCC compacts, only the bottom face showed a lower Brinell hardness.


CONCLUSIONS
Except for Brinell hardness measured on MCC compacts, the tested samples were characterized by anisotropic mechanical properties when its porous structures were sometimes anisotropic. Then, there is not a straight link between porosity anisotropy and mechanical properties.
Porion
Patrice
P
Centre de Recherche sur la Matière Divisée-UMR 6619, CNRS and Université d'Orléans, 1 Bis Rue de la Férollerie, 45071 Orléans Cedex 2, France.
Busignies
Virginie
V
Mazel
Vincent
V
Leclerc
Bernard
B
Evesque
Pierre
P
Tchoreloff
Pierre
P
D016880:Anisotropy; D002130:Calcium Phosphates / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry*; D004339:Drug Compounding; D006244:Hardness; D006245:Hardness Tests; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D016062:Porosity; D013499:Surface Properties; D013607:Tablets / Q000737:chemistry*; D013718:Tensile Strength
D002130:Calcium Phosphates; D013607:Tablets; D002482:Cellulose; C020243:calcium phosphate; C109691:microcrystalline cellulose