Particle design by surface modifications: spray-drying and co-granulation of mannitol/sorbitol mixtures

The effect of granulation processing conditions on the surface morphology o f mannitol/sorbitol granules was investigated in a bottom spray fluidised b ed granulator: Aqueous mannitol/sorbitol solutions were sprayed onto cove p articles comprising small glass beads or anhydrous dicalcium phosphate lead ing to the formation of characteristic needle-shaped crystals or platelets. Granule-properties, namely, surface morphology, mean diameter and particle size distribution, residual moisture content and thermal properties were d etermined The tabletting properties of the the granules were compared. The surface I,morphology was found to be mainly influenced by the water content of the inlet air followed by the inlet air temperature. According to diffe rential scanning calorimetry (DSC) and X-ray diffraction (XRD) measurements , the polyols do not recrystallise separately from solution. It is likely t hat sorbitol is integrated as a disruptive factor in the crystal lattice of mannitol. Thus, small needle-like crystals are formed The tabletting of gr anules shows a strong correlation between the crushing strength and humidit y of the granular material.