Particle design of tolbutamide by the spherical crystallization technique. III. Micromeritic properties and dissolution rate of tolbutamide spherical agglomerates prepared by the quasi-emulsion solvent diffusion method and the solvent change method

With the objective of modifying the micromeritic properties of tolbutamide (i.e., to manufacture a highly functional powder form), particle design was attempted using a quasi-emulsion solvent diffusion (QESD) method, and the micromeritic properties and dissolution rate of the obtained spherical agglomerates were evaluated by comparison with agglomerates prepared by the solvent change (SC) method. For the production of tolbutamide agglomerates by the QESD method, a necessary condition was the addition of a sucrose fatty acid ester to the system as an emulsifying agent. The particle diameter of the agglomerates obtained by the QESD method depended on the size of the initially formed quasi-emulsion droplets, which in turn depended on the viscosity of the solution. In addition, the agglomerates were nearly perfectly spherical in shape. In the QESD method, the quasi-emulsion droplets crystallized instantaneously from the droplet surface inward. The resultant agglomerates were dense, had great mechanical strength and showed excellent flowability due to their perfect spherical shape. On the other hand, the agglomerates produced by the SC method were conglomerates of primary crystals, and fine, needle-like crystals formed on their surface. As a result, these agglomerates had a large specific surface area, and they therefore showed greater solubility than the agglomerates prepared by the QESD method.