The Role of Excipients in Pharmaceutical Powder-to-Tablet Continuous Manufacturing

Abstract

The pharmaceutical industry is continuously looking for strategies and solutions that can improve quality and efficiency of manufacturing processes. As a result, there has been a significant shift towards continuous manufacturing (CM). Traditionally, tablets have been produced by batch processes, in which all ingredients are discharged in one unit operation. Production stops and material is removed after each processing step. In contrast, in a continuous process there are no discrete process steps and material is gradually moving through the different operating units.

In spite of the increasing interest the pharmaceutical industry, CM is still new to many pharmaceutical companies. Much knowledge has been established on the role of raw material properties in batch processing, but this knowledge is not directly transferable to continuous processes. In order to enable the transition from batch production to continuous production, each processing step needs to be re-designed. The design of robust continuous processes requires a thorough understanding of the impact of material properties on each unit operation in a continuous manufacturing line.

In this thesis, the role of excipients for continuous manufacturing of tablets is evaluated. Unit operations that are discussed include feeding, blending, dry granulation, lubricant blending, and die filling. Integrated continuous direct compression processes are also evaluated and compared to batch processing. Additionally, the impact of material properties on the disintegration performance of tablets are discussed. The thesis concludes with an expert opinion on existing gaps in the industry to optimize the use of excipients in continuous manufacturing processes.

1.5. Thesis outline

In the current thesis, the role of excipients for continuous powder-to-tablet manufacturing is evaluated. Unit operations that are discussed include feeding, blending, granulation and tableting. Other unit operations, like coating or packaging, are kept out of scope.

Chapter 2 is focused on the first unit operation in all continuous powder-to-tablet lines. The effect of intra and inter batch variation on the performance of feeders is described.

Chapter 3, 4 and 5 continue with the next unit operation, which is blending. In chapter 3 and chapter 4 batch and continuous blending of binary and ternary mixtures are compared. Chapter 5 is focused on high shear blending processes. It is described how the material chemistry and morphology impact the attrition behavior of excipients during high shear blending.

Chapter 6 and chapter 7 focus on the effect of excipient deformation mechanism in continuous dry granulation processes for tablet production. In chapter 6, the evaluation centers on three commonly used components in tablet formulations, i.e. lactose monohydrate, anhydrous lactose and microcrystalline cellulose. The impact of particle size on the reduction of compactability after roller compaction is analyzed. Chapter 7 focuses on the role of superdisintegrants, which are minor components in the formulation. It is discussed how superdisintegrants contribute to a reduction in the loss of compactability in anhydrous lactose based formulations.

Lubricant blending is discussed in chapter 8. Here, a direct comparison is made on the lubricant sensitivity of anhydrous and granulated lactose in batch and continuous blending processes.

In chapter 9 the role of powder properties in the die filling process are described. It is revealed how the particle size distribution can impact the rheological behavior of excipients.

Chapter 10 and chapter 11 contain evaluations on a fully integrated continuous manufacturing process. The impact of a broad set of material properties and process parameters on the final tablet quality in a continuous direct compression line are described, and compared to batch processes.

The role of material properties on the disintegration performance of a tablet is explored in chapter 12 and chapter 13. Chapter 12 contains a review describing the functional related characteristics of superdisintegrants. In chapter 13, the material properties of lactose that impact tablet disintegration are revealed.

The thesis concludes in chapter 14 with a review including an expert opinion on existing gaps in the pharmaceutical industry to optimize the use of excipients in continuous manufacturing processes for the production of tablets. This part will discuss amongst others the need of understanding functional related characteristics of excipients, excipient variability, co-processed excipients with multifunctional properties and digitalization.

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Janssen, P. (2024). The Role of Excipients in Pharmaceutical Powder-to-Tablet Continuous Manufacturing. [Thesis fully internal (DIV), University of Groningen]. University of Groningen. https://doi.org/10.33612/diss.1135462083