Browsing by Subject "continuous wet granulation"

Pharmaceutical industry is in a process of adopting new technologies due to the growing interest towards the continuous manufacturing approach. However, while the continuous wet granulation process with twin-screw granulator (TSG) has been studied widely, there has been less focus on subsequent continuous granule drying process. As a result, truly continuous granule drying device has not been available for a long time. However, L.B. Bohle has introduced a horizontal truly continuous fluid bed dryer (CFBD) in form of a perforated belt. In such system the wet granules are transported via vibration along the bed without actual fluidization while the hot air dries the granules. Accordingly, Bohle QbCon-25 fully integrated powder-to-tablet system facilitates the combination of a TSG and CFBD. However, the combination is relatively new and only few studies using these methods are available. Aim of this study was to experimentally evaluate the novel Bohle’s CFBD and elucidate the effect of formulation and process parameters of TSG and CFBD on granule residual water content. Additionally, the granules were characterized by their size distribution and bulk and tapped densities. Granule temperature and residence time in the dryer was determined with CubiSens mini sensors. In total 84 wet granulation trials in design of experiments setup were performed and multiple linear regression (MLR) model was used to investigate the effects of different process parameters on granule loss-on-drying (LoD) response. As a result, formulation microcrystalline cellulose (MCC) amount and all studied process parameters of TSG and CFBD showed significant effect on drying result indicating a robust manufacturing process. The increase in the amount of MCC in the formulation as well as the increase in L/S ratio and line rate in the wet granulation was reflected in a higher residual water content in dried granules. However, with increased drying time, airflow rate and inlet air temperature the granule residual water content decreased. The most influential process parameter affecting the granule residual water content was the used L/S ratio. In contrast, the material acceleration which corresponds to the granule drying time was the most significant process parameter of the CFBD affecting the granule residual water. However, the material acceleration did not only correspond to the material residence time in the dryer, but also to the thickness of the granule bed in the dryer. This indicated that the material acceleration is a critical process parameter of the CFBD. However, the thickness of the granule bed could not be measured in real time in this study. Additionally, at intense drying conditions granules showed a very dry outcome and further studies are required to elucidate the operational limit of the CFBD device. Furthermore, the vibration during the drying phase did not have an effect on granule size or the bulk and tapped densities. Material behavior in system was plug-flow like and mean material residence time in the CFBD was only 40 seconds with the middle material acceleration setting. Moreover, the temperature of the granules rose close to the process air temperature, but only for a very short time. Additionally, the used process settings in wet granulation affected the granule temperature, however, the most influential factor on the granule temperature was the used inlet air temperature. Overall, Bohle QbCon25 manufacturing system with TSG and CFBD showed high suitability to wet granulate and dry the produced granules with a uniform residual water content up to 20 kg/h throughput rate without process instability issues.