Effect of binder and load solubility properties on HPMC granules produced by wet granulation process

Hydroxypropyl methylcellulose (HPMC) is one of the most important hydrophilic ingredients used in hydrogel matrices preparation (tablets or granules). In this work, HPMC was used to produce granules loaded with hydrophilic and hydrophobic active molecules to investigate their possible use as release dosage forms for pharmaceutical and nutraceutical applications. Unloaded and vitamins loaded HPMC granules were produced by wet granulation to investigate the effect of molecule solubility and granulation liquid type, on physical, mechanical and release properties. Water-soluble vitamin B12 and water-insoluble vitamin D2 were used as model molecules. Due to their different solubility, two granulation liquid phases were also used: distilled water for granules with B12, and ethanol-water for granules with D2. Results showed that use of ethanol in the liquid phase reduces the granulation yield and produces granules having a less defined shape, a smaller mean size, a less hard structure and a worse flowability. Moreover, ethanol slightly enhances the polymer erosion rate. Results also emphasized that the vitamins solubility does not affect either the physical and the mechanical properties of the produced granules. However, it plays a significant relevant role on the molecule release mechanism, being B12 and D2 were released by diffusion and erosion mechanism, respectively.