How spherical crystallization improves direct tableting properties: a review

Direct tableting has been renewed as a preferable process by simply mixing and compressing powder to save time and cost in comparison with granule tableting. Direct compression tableting as a technique has been successfully applied to numerous drugs on the industrial scale, although the success of any procedure, and resulting mechanical properties of tablets, is strongly affected by the quality of the crystals used. Good flowability, packability and compactability are prerequisite for drug to be prepared by direct tableting. When the mechanical properties of the drug particles are inadequate a primary granulation is necessary. The use of spherical crystallization as a technique appears to be an efficient alternative for obtaining suitable particles for direct tableting. Spherical crystallization is a particle design technique, by which crystallization and agglomeration can be carried out simultaneously in one step and which has been successfully utilized for improvement the micromeritic properties of crystalline drugs. In this review, we will discuss how the micromeritic properties of the particles such as flowability, packability and compactability can be improved by spherical crystallization technique.