Loss-in-weight feeding, powder flow and electrostatic evaluation for direct compression hydroxypropyl methylcellulose (HPMC) to support continuous manufacturing

Minimizing variability in the feeding process is important for continuous manufacturing since materials are fed individually and can impact the final product. This study demonstrates the importance of measuring powder properties and highlights the need to characterize the feeding performance both offline with multiple refills and in the intended configuration for the continuous manufacturing equipment.

The standard grade hydroxypropyl methylcellulose (HPMC) had material buildup on the loss-in-weight feeder barrel from triboelectric charging and resulted in more mass flow excursions and failed refills which were not observed with the direct compression grades. The location of the electrostatic buildup changed when the feeder was connected to a hopper instead of feeding offline into a collection bucket. Overall, the direct compression HPMC exhibited better flow which resulted in more accurate loss-in-weight feeding with less excursions from the target mass flow and all refills were completed in the first attempt.

The improvements with the direct compression HPMC would be beneficial when running any continuous process (wet granulation, roller compaction, or direct compression) or other processes where loss-in-weight feeding is utilized, such as melt extrusion or twin screw granulation. Continue on Loss-in-weight feeding, powder flow and electrostatic evaluation for direct compression hydroxypropyl methylcellulose (HPMC) to support continuous manufacturing

Materials

Six different Benecel^TM Hypromellose lots (Ashland Inc. Wilmington, DE) consisting of three standard CR grades of HPMC K100M, K15M, K4M and three new DC (Direct Compression) grades of HPMC K100M, K15M, K4M.

Interesting remark on the Tapped Density Measurement

Tapped density

The automated GranuPack (Granutoools, Awans, Belgium) removes much of the inaccuracy with traditional tapped density tests where the measurements are estimated by eye using a graduated cylinder. The interpretation of the result with traditional testing is especially difficult for the initial measurement since the powder surface is very erratic after pouring powder into the graduated cylinder. The GranuPack instrument also provides more information around the progression of the density change over time by taking a distance measurement after every tap and not just the final value. The test method consisted of adding approximately 11 g of sample into a grounded metallic initialization tube. Check the latest information on GranuPack High Temperature