Analysis of the compression mechanics of pharmaceutical agglomerates of different porosity and composition using the Adams and Kawakita equations.
OBJECTIVE
To analyze the mechanics of some pharmaceutical agglomerates during uniaxial confined compression by using compression parameters derived from the Heckel, Kawakita and Adams equations, and to study the influence of these compression parameters on the tablet-forming ability of agglomerates.


METHODS
Force and displacement data sampled during in-die compression of agglomerates was used to calculate compression parameters according to the Heckel (sigmay), Kawakita (1/b and a), and Adams (tau0') equations. Mechanical strength of single agglomerates as well as the air permeability and tensile strength of tablets prepared from them were also determined.


RESULTS
Sigmay- from the Heckel equation did not differ between agglomerates of different porosity. Both 1/b and tau0' varied with agglomerate porosity and composition. These two compression parameters were linearly related to each other. No general correlation was found between 1/b and tau0' and the strength of single agglomerates. The two parameters were related to the intergranular pore structure and tensile strength of tablets formed from the agglomerates.


CONCLUSIONS
1/b and tau0' may be interpreted as measures of the agglomerate shear strength during uniaxial confined compression, and as such they may be used as indicators of the tabletting performance of the agglomerates.
Nicklasson
F
F
Department of Pharmacy, Uppsala University, Sweden.
Alderborn
G
G
D000465:Algorithms; D004339:Drug Compounding / Q000706:statistics & numerical data*; D006245:Hardness Tests; D008962:Models, Theoretical; D010539:Permeability; D016062:Porosity; D011208:Powders; D011312:Pressure; D013718:Tensile Strength
D011208:Powders