Particle design of naproxen-disintegrant agglomerates for direct compression by a crystallo-co-agglomeration technique

The purpose of the present research was to obtain directly compactible agglomerates of naproxen containing disintegrant by a novel crystallo-co-agglomeration (CCA) technique. Acetone–water containing hydroxypropylcellulose (HPC) was used as the crystallization medium. Acetone acted as a good solvent for naproxen as well as a bridging liquid for agglomeration of crystallized drug with disintegrant and aqueous phase as non-solvent. The agglomerates were characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (XRPD) and scanning electron microscopy. The agglomerates were compressed at different compression pressures and dissolution studies were carried out for the tablets produced at lowest compression force. The growth of particle size and the spherical form of the agglomerates resulted in formation of products with good flow and packing properties. The improved compaction properties of the agglomerated crystals were due to the fragmentation which occurred during compression. DSC and XRPD studies showed that naproxen particles, crystallized in the presence of HPC and disintegrant did not undergo structural modifications. The dissolution rate of naproxen from the agglomerates could be controlled by the amount of included disintegrant, being enhanced as the latter was increased. Moreover, the results showed that when the disintegrants were included both intragranularly and extragranularly during agglomeration of naproxen particles, tablets containing these agglomerates dissolved at a faster rate than the tablets containing crystallized naproxen with the same amount of disintegrant incorporated only extragranularly by physical mixing. In conclusion, the properties of agglomerated crystals, such as flowability, compactibility and dissolution rate were improved profoundly using the developed technique resulting in successful direct tableting without need to additional process of physical blending of agglomerates and disintegrants.