Use of a moist granulation technique (MGT) to develop controlled-release dosage forms of acetaminophen

The moist granulation technique (MGT), which involves agglomeration and moisture absorption, has only been applied to immediate-release dosage forms. Our results indicate that MGT appears to be applicable in developing a controlled-release formulation. A small amount of granulating fluid (water) was added to a powder blend to activate a dry binder (such as polyvinylpyrrolidone [PVP] at 2% and 3.6%) and to facilitate agglomeration. Then, a moisture-absorbing material (microcrystalline cellulose [MCC]) was added to absorb any excess moisture. By adding MCC in this way a drying step was not necessary. Acetaminophen (APAP) was the model drug, with diluents lactose FastFlo(R) and dicalcium phosphate. Hydroxypropylcellulose (HPC) was used as the controlled-release agent. The MGT was compared to conventional wet granulation (WG) and direct compression (DC) processing methods. The results indicate that MGT appears to be applicable in developing a controlled-release formulation. Particle size distribution of MGT and WG batches containing 3.6% PVP is similar.