Fluidized-Bed agglomeration of acetaminophen; direct compression of tablets and physiologic availability

A novel process was developed for manufacturing acetaminophen in a free-flowing, directly compressible agglomerated form, involving spray agglomeration of acetaminophen powder with polyvinylpyrrolidone (PVP) in isopropyl alcohol as a bonding agent using a fluidized-bed granulator. Agglomerates prepared with 5% PVP yielded a free-flowing and compressible material. Upon lubrication with 0.5% magnesium stearate, the material was found to be directly compressible into tablets. To improve dissolution and tableting properties, the agglomerates were compressed into tablets after blending with varying weight ratios of microcrystalline cellulose/pregelatinized starch as a filler/disintegrant combination. The final stable tablet formulation consisted of agglomerates equivalent to 325 mg of acetaminophen, 2.1 mg of magnesium stearate, and the filler/disintegrant in a weight ratio of 70:30 to yield a tablet weight of 425 mg. Physical properties and dissolution profile of these tablets were comparable to those of a commercial acetaminophen tablet. Physiologic availability calculated using the urinary excretion method indicated half-lives of 2.0, 2.1, and 2.2 hours for control (acetaminophen powder), experimental tablet, and a marketed product, respectively.