ABSTRACT
This paper focuses on investigating the influence of varying barrel fill levels on the mean residence time, granule properties (median size, size distribution, and shape), and tensile strength of tablets. Specific feed load (SFL) (powder feed rate divided by screw speed) and powder feed number (PFN) (i.e., powder mass flow rate divided by the product of screw speed, screw diameter, and the material density in the denominator) were considered as surrogates for the barrel fill level. Two type of powders (lactose and microcrystalline cellulose (MCC)) were granulated separately at varying fill levels at different liquid-to-solid ratios (L/S). It was observed that by controlling the barrel fill level, the granule size, shape, and tablet tensile strength can be maintained at specific L/S. It was also noticed that the mean residence time decreased with increasing fill levels in the case of both lactose and MCC powder. However, it was only found to be related to the change in granule size in case of granulating microcrystalline cellulose at varying fill levels. At very high fill levels, granule size decreased, owing to a limited interaction between MCC powder and liquid at high throughput force and short residence time.
ABSTRACT
Lactose and mannitol are some of the most commonly used powders in the pharmaceutical industry. The limited research published so far highlights the effects of process and formulation parameters on the properties of the granules and the tablets produced using these two types of powders separately. However, the comparison of the performance of these two types of powders during twin screw wet granulation has received no attention. The present research is focused on understanding the granulation mechanism of different grades of two pharmaceutical powders with varying properties (i.e., primary particle size, structure, and compressibility). Three grades each of lactose and mannitol were granulated at varying liquid to solid ratios (L/S) and screw speed. It was noticed that primary powder morphology plays an important role in determining the granule size and structure, and tablet tensile strength. It was indicated that the processed powders such as spray-dried and granulated lactose and mannitol can be used in formulation for wet granulation where flowability of active pharmaceutical ingredient (API) is poor.
