Continuous manufacturing of tablets has many advantages, including batch size flexibility, demand-adaptive scale up or scale down, consistent product quality, small operational foot print, and increased manufacturing efficiency. Simplicity makes direct compression the most suitable process for continuous tablet manufacturing. However, deficiencies in powder flow and compression of active pharmaceutical ingredients (APIs) limit the range of drug loading that can routinely be considered for direct compression. For the widespread adoption of continuous direct compression, effective API engineering strategies to address power flow and compression problems are needed. Appropriate implementation of these strategies would facilitate the design of high-quality robust drug products, as stipulated by the Quality-by-Design framework. Here, several crystal and particle engineering strategies for improving powder flow and compression properties are summarized. The focus is on the underlying materials science, which is the foundation for effective API engineering to enable successful continuous manufacturing by the direct compression process.

• GlaxoSmithKline Pharmaceuticals R&D

• Oral solid dose
• Material and process characterization

1. continuous manufacturing
2. crystal engineering
3. Direct compression
4. Formulation design
5. Material and process characterization
6. oral solid dose
7. Particle engineering
8. quality by design
9. Research Article