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Understanding Powder Behavior in Continuous Feeding: Powder Densification and Screw Layering

By Sara Fathollahi1; Pauline H. M. Janssen2; Bram Bekaert3; Dirk Vanderroost4; Valerie Vanhoorne3; Bastiaan H. J. Dickhoff1

1. DFE Pharma 2. DFE Pharma, Department of Pharmaceutical Technology and Biopharmacy, University of Groningen 3. Laboratory of Pharmaceutical Technology, Department of Pharmaceutics, Ghent University 4. GEA Process Engineering

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Category

Peer-reviewed journal

Published on

Abstract

Background: Precise continuous feeding of active pharmaceutical ingredients (APIs) and excipients is crucial in a continuous powder-to-tablet manufacturing setup, as any inconsistency can affect the final tablet quality. Method: This study investigated the impact of various materials on the performance of a continuous twin-screw loss-in-weight (LIW) feeder. The materials tested included spray-dried lactose, anhydrous lactose, granulated lactose, microcrystalline cellulose (MCC), an MCC–lactose preblend (50%:50% w/w ratio), and a co-processed excipient (lactose–lactitol at a 95%:5% w/w ratio). The feeding performance of these excipients was systematically assessed, focusing on powder densification and screw layering within the LIW feeder. Results: The results demonstrated densification for the spray-dried lactose and preblend. Densification was more pronounced during the initial feeding cycles for spray-dried lactose, but decreased gradually over time. In contrast, the densification remained relatively constant throughout the feeding process for the preblend. Notably, minor screw layering was observed for both spray-dried lactose and anhydrous lactose, with the extent of this issue reducing over time for the spray-dried lactose. Interestingly, granulated lactose grades did not show screw layering, making them preferable for blending with APIs prone to severe screw layering. The LIW feeder control system successfully managed powder densification and minor screw layering, maintaining the mass flow rate at the set point for all investigated materials. Conclusions: These findings inform the selection of optimal excipients, appropriate tooling for LIW feeders, and the enhancement of control strategies to shorten startup times. By addressing these factors, the precision and reliability of continuous feeding processes can be improved.

Journal

Powders

DOI

10.3390/powders3040026

Type of publication

Open Access Journal

Affiliations

  • DFE Pharma
  • Department of Pharmaceutical Technology and Biopharmacy, University of Groningen
  • Laboratory of Pharmaceutical Technology
  • GEA Process Engineering

Article Classification

Peer-Reviewed Journal

Classification Areas

  • API
  • PAT

Tags

  1. API
  2. Continuous feeding
  3. co-processed
  4. densification
  5. Excipient
  6. feed factor variation
  7. Lactose
  8. loss-in-weight (LIW) feeder
  9. preblend
  10. screw layering