The effects of formulation factors on the moist granulation technique for controlled-release tablets

Controlled-release tablets were prepared by the moist granulation technique (MGT), a granulating method that uses very limited amounts of liquid and requires microcrystalline cellulose (MCC) to absorb moisture. Acetaminophen (APAP) was the model drug, and the polymer hydroxypropylcellulose (HPC) served as the controlled-release agent. The effects of varying drug, binder (polyvinylpyrrolidone, PVP), polymer, and MCC levels on granule properties and tablet dissolution were studied. Dissolution testing was carried out in distilled water using the USP paddle method. In all cases, the granules flowed and compressed well. The granule properties were evaluated by calculating the mean particle size for all batches from sieve analysis data. The results indicate that MGT can be applied to control drug release, and at a polymer content of 44.6% or more, the process is robust enough to allow slight variations in formulation factors without affecting drug release.