Bioscience seminar series

  • Datum: –09.45
  • Plats: Join Zoom Meeting
  • Föreläsare: Professor Göran Alderborn and Maryam Tofiq, MSc in Pharmacy, PhD student, from the Pharmaceutical technology research group.
  • Arrangör: Bioscience Seminar Team
  • Kontaktperson: Anna Nilsson
  • Seminarium

Compression and compaction properties of granular solids

High technical demands are placed on a powder that should be compacted into tablets to ensure robust, quality assured manufacturing. A common approach to confer needed technical properties to a fine powder is granulation. Granulation is a size enlargement process, i.e. larger particles are formed from finer particles, and improved technical powder properties can be obtained while the size of the original drug particles are approximately preserved. The manufacturing classification system describes four manufacturing routes for tablets among which the use of wet and dry granulation are two routes. Recently, the use of dry granulation technologies has increased since dry granulation enables continuous tablet manufacturing.

By wet granulation, fine particles are bonded together into granules by a liquid. Using a special type of wet granulation technology, model granular solids in the form of spherical particles of uniform size could be prepared. By studying such model granules, a theoretical framework for granule engineering has been developed. Key aspects are the microstructure and the plastic stiffness of the granules which control the evolution in microstructure and hence tensile strength of the tablets during compression.

During dry granulation, a blend of fine powders is compressed into compacts, typically by roller compaction, and the force applied to the drug particles are considerably higher than needed during wet granulation. The compacts are thereafter milled, mixed with additional excipients and (re)compressed to obtain the final tablets. The granules obtained by dry granulation are small, irregular particles which mechanical properties probably differ from wet granulated particles, especially the brittleness. The same mechanistic conception as developed for wet granulated particles may hence not be applicable to dry granulated particles. A study is now initiated with the objective to investigate the compression and compaction properties of some dry granulated powders. In order to vary the strength of the dry granulated particles, granules were prepared from a systematically varied excipient ratio of a plastic and a brittle fine powder and with known different tablet forming ability, i.e. crystalline -lactose monohydrate and microcrystalline cellulose. In order to assess the mechanical properties of the granules, analytical powder compression rather than single particle testing is used. It is shown that the compressibility of the granular solids is controlled by their relative bulk density independent of the composition while the granule compression strength depends on the combined effect of composition and porosity of the granules.