Skip to main content
Login | Suomeksi | På svenska | In English

Browsing by Subject "dry granulation"

Sort by: Order: Results:

  • Saarinen, Tuomas (2015)
    The roller compaction is a dry granulation method which is commonly used in the pharmaceutical industry. The purpose of the roller compaction is to increase the particle size, narrow the particle size distribution and improve the powder flowability. In the roller compaction process, powder is fed between two press rolls. The relevant process parameters of the roller compaction (roll pressure, roll speed and feed screw speed) affect the formed briquette or ribbon density. The briquette is broken down and sieved by using a crusher. General problems of the roller compaction are incompressible fine powder and the low yield. AGS (Aerodynamic Granulating System) is a patented supplement for the roller compaction. Its operation is based on the air flow which sucks the fine particles out of the granule mix. The granules and the fine particles are collected into their own containers. When the system is fully optimized the fine particles can be recycled between the press rolls (a closed loop). In this case, it is possible to get close to 100 % batch yields. The experimental design of this study was a modified central composite design with three variables and two value levels which was used to find the optimal combinations of the process parameters. The purpose of this study was to compare the gas assisted and the conventional roller compaction methods. The physical properties of granules and tablets made of these granules were compared. The strengths and weaknesses in AGS process were also studied and development ideas for the future were planned. Microcrystalline cellulose was used in this study as a model excipient. The study showed that the granules made by the AGS require higher compression forces in tableting process than conventional granules. The reason for this could be the lower number of contact points between the particles, since the fine particles were removed from the granule mix. The low compression pressure, fairly fast roll speed and small sieve size created good quality granules. The flowability and compression properties of these granules were good as well as particle size distribution. In this study, any major differences were not observed between these two granulation methods.
  • Heiman, Johanna (2012)
    This work evaluated the use of roller compaction as granulation method for hydroxypropyl methylcellulose (HPMC) based hydrophilic extended release matrix tablets. Roller compaction is a dry granulation method where powder material is fed through a hopper between two counter-rotating rolls and pressed into a ribbon like compact. The compact is thereafter milled to obtain granules. Two full factorial experimental designs (DoE) were set up using two model active pharmaceutical ingredients (API). Paracetamol was chosen as a model for a highly soluble API that deforms mainly by fragmenting, whereas ibuprofen was used as a model for poorly soluble and plastically deforming API. The effect of process parameters, the roll pressure and the ratio between feeder screw speed and roll speed as well the effect of particle size of API and HPMC on the manufacturability and release robustness were investigated. Both compositions with medium drug load were successfully compacted into ribbon. Roller compaction increased the particle size and bulk density of the tablet mass. However, the methods used for evaluation of flow properties gave contradictive results on whether the flow properties were enhanced after dry granulation. The loss of compactibility after granulation was observed, as the tensile strength of tablets prepared of granules was in most cases lower than that of directly compacted powder. Exceptionally, two of the ibuprofen granulations showed compactibility similar to that of the initial powder blends. Increased roll pressure resulted in denser ribbon and narrower particle size distribution for granules. However, high roll pressure had a tendency to decrease the tablet tensile strength. This is most probably due to the particle size enlargement and work hardening phenomenon during the double compaction. The use of large particle size HPMC improved the permeability of the powder blend and the flow properties of the granulations. Tablet dissolution testing showed that the large sized HPMC particles were unable to percolate through the tablet and form a consistent network. Roller compaction helped to break down the large HPMC agglomerates and distribute them more evenly within the tablets. No significant difference in release profiles was observed for tablets prepared using granules roller compacted with different parameters.