Effect of Equipment Parameters on Amount and Dispersion of Wetting Liquid in Planetary Centrifugal Granulation

In planetary centrifugal wet granulation, the binder is often mixed into the formulation as a powder, followed by the addition of a wetting liquid, in a single step. Therefore, the amount and dispersion of the wetting liquid are important factors that determining granulation success and granules characteristics. In this study, granulation experiments, according to the Box-Behnken design, were performed. Further, the effects of equipment parameters, namely, processing speed, processing time, and vessel size, on the minimum amount of wetting liquid required to enable granulation and dispersion state in the vessel were statistically analyzed. Placebo granules were formulated with lactose hydrate and corn starch (7 : 3), using sodium carmellose as a binder. Results showed that the amount of wetting liquid decreased with increase in processing speed, processing time, and vessel size; however, the dispersion state of the wetting liquid was not significantly affected. Analysis of the effects of the equipment parameters on granule characteristics showed that a larger vessel size was proportional to a larger median diameter and smaller particle-size distribution width (span), and a faster processing speed was proportional to a smaller span. Furthermore, granules with the target properties could be prepared according to the parameters estimated from the model. In conclusion, the equipment parameters for controlling the amount of wetting liquid, which affected the granule properties, were clarified.

Small-Scale Spherical Granulation Using a Planetary Centrifugal Mixer

A concise spherical granulation method is required to prepare extemporaneously granules remanufactured from oral dosage forms for administration to individuals who cannot swallow tablets or capsules. In this study, we determined the feasibility of spherical granulation using a planetary centrifugal mixer. A model formulation, 20% ibuprofen (IBP) granules, was prepared using a lactose/cornstarch (7 : 3, w/w) mixture or D-mannitol as diluents, and changes in granule characteristics (mean diameter (d50), distribution range of granule size (span), and yield) were evaluated according to the amount of water added and the granulation time. The amount of water was assessed using the plastic limit value as measured using a digital force gauge. We successfully produced granules, and larger amounts of water and longer granulation times resulted in larger d50 values and smaller span values. The optimal granulation time was 45 s and the optimal water contents were 70 and 67.5% of the plastic limit value for the lactose/cornstarch mixture and D-mannitol, respectively. When compared to commercial 20% IBP granules, powder X-ray diffraction and differential scanning calorimetry analyses showed that the granulation process did not alter the crystallinity of the drug. Thus, this novel granulation method using a planetary centrifugal mixer may be a promising technique for compounding in pharmacies and in pharmaceutical manufacturing.