A platform and process that involves a combination of liquids and solids, via a variable intensity motive force (typically high shear or low shear mixing in a granulator) working the powders and creating a dense granule that can be compressed or encapsulated.
Wet granulation is the process of joining powder particles together to create a larger particle, known as a granule. The granules can be composed of particles that are either the same or dissimilar materials depending upon the formulation ingredients. In the wet granulation process, granules are joined together using a binder solution, often aqueous, that is sprayed into the process.
The two primary types of wet granulation are high shear and low shear.
In the case of high shear, the binding solution is introduced to the dry particles in a vessel that has a motor-driven blade or impeller system that creates a variable intensity (or high shear force) interaction. The most common piece of equipment for this process is a vertical or horizontal (top drive or bottom drive) high shear granulator.
In the case of low shear, the binding solution is introduced to the dry particles in a vessel, via a spray atomization configuration that creates a softer (or low shear force) interaction. The most common piece of equipment for this process is a fluid bed granulator.
|Reasons for wet granulation:|
- Dust reduction: reduces fine particles for better dust control during processing
- Improved flowability: improves the overall flowability of powders, which is more conducive to downstream processing requirements
- Particle size and uniformity control: can predetermine the final granule size and create a consistent distribution of ingredients
- Compaction enablement: good granulation helps hold the granules together when they are compressed into a tablet core
- Controlled solubility characteristics: increases control of the dissolution profiles
- Increased bulk density: a key process parameter control for specific body absorption
|Main pieces of wet granulation equipment:|
- Granulator: This is a system that creates the motion and energy to integrate solids and liquids efficiently and under control.
- Solution delivery system: This is the device that delivers the granulating liquid to the powders. It generally consists of a solution delivery tank, pump system, piping, and spray nozzles.
- Dryer: A fluid bed dryer removes the liquids and dries the powders after the wet granulation process creates the desired granule characteristics.