The Advantages Of Fluid Bed Granulation

During fluid bed granulation, high-velocity air is used to suspend powdered material within a Fluid Bed Granulator. This specialized, multi-purpose piece of equipment is capable of mixing, granulating, and drying, obviating the requirement to use separate instrumentation for each stage of the process. Designed to introduce the air stream into the bed from below, the fluid bed granulator expands the bed upward to provide high heat and mass transfer surface area. This process can also be microwave-assisted to provide much faster drying rates and lower operating temperatures.

Next, a binder is sprayed onto the powder, causing the particles to stick together and form granules. This occurs via a stage wise process of moistening and solidifying to give rise to agglomerates. A wide variety of binders can be employed, including aqueous or organic solvents, as well as dissolved polymeric materials.

In addition to reduced costs and space requirements as a result of combining multiple processes within the same specialized instrument, fluid bed granulation offers many further advantages. Firstly, it is highly reproducible since the capacity to control the air flow and the ability to dictate the rate at which the binder is sprayed onto the powdered material afford extremely tight control over granule size. Drying is fast and homogeneous, with no problematic hot spots since the granules do not encounter the drying surface but are instead suspended. Fluid bed granulation is easier to scale and affords more accurate prediction of product attributes than high-shear applications. Furthermore, timings can be normalized between manufacturing runs to ensure the production of highly uniform material.

The granulation process is typically followed by steps such as sizing, blending, and compression. Of these, sizing can be especially costly and time-consuming. Techniques such as sieve analysis, image analysis, and laser diffraction all require the use of specialized equipment and necessitate the granulation process to be paused while sampling is carried out. The incorporation of fluid bed granulation into pharmaceutical manufacturing processes can often eliminate sizing through enhanced particle size distribution (PSD) control.