Development of spherical crystal agglomerates of an aspartic acid salt fordirect tablet making

Agglomerates of an aspartic acid salt were developed by means of a non-typi cal spherical crystallization technique. The aspartic acid salt was crystal lized by a salting-out method combined with cooling. Traditional mechanical stirring crystallization (samples A and B) and the recirculation process ( sample C) were used. The control material was commercial aspartic acid salt with very poor flowability and compressibility. The particle sizes of the samples were measured by sieve analysis. The morphology of the crystals and crystal agglomerates was controlled by SEM. The specific surfaces of the p roducts were determined by the BET method and the micropore volumes were ca lculated via the BJH theory. The Carr index, rearrangement constant, plasti city and compressibility values were calculated. The samples were controlle d by thermoanalytical investigations (TG, DTG and DSC). Both of the crystal lization techniques used resulted in spherical agglomerates of the aspartic acid salt with very good flowability and compressibility parameters. Prima rily sample B, with a closed "cauliflower-like" structure, can be suggested for tablet making involving a large mass (e.g., chewable tablets) by direc t tablet pressing. Faster initial cooling rate and slower stirring rate wer e very favourable in the building-up of crystal agglomerates of sample B wi th a closed structure and a large particles. Sample B can be suggested furt her for capsule filling because of its high poured density, very good flowa bility and fast rearrangement. (C) 2001 Elsevier Science S.A. All rights re served.