1. INTRODUCTION
Granulation process has been widely used in the pharmaceutical industry for the preparation of material for tabletting.
Other Granulation process involves the granule formation includes microencapsulation, multi particulate system for modified release mechanism and to prepare granules to improve flow and compression characteristics of the blend.
What is Granulation?
Granulation may be defined as a size enlargement process which converts fine or coarse particles into physically stronger and larger agglomerates having good flow property, better compression characteristics and uniformity. OR
The art and science for process and production of granules is known as Granulation Technology.

2. ADVANTAGES
It improves flow property and compression characteristics
and increases density of granules.
Better distribution of color and soluble drug if added in the
binding solution.
It reduces dust hazards.
Prevents segregation of powders.
Makes hydrophobic surfaces more hydrophilic.
DISADVANTAGES
Process is expensive because of labor, space, time special equipment and energy requirement.
Loss of material during various stages of processing.
Moisture sensitive and thermo labile drugs are poor candidates.
Any incompatibility between the formulation components is aggravated during the processing.

3. Methods of granulation
DIRECT COMPRESSION
DRY GRANULATION
WET GRANULATION
DIRECT COMPRESSION
This method involves simple blending of active pharmaceutical ingredient (API) with other ingredients and direct compaction of the resultant mixture.
Advantages of Direct compression
1. Cost Effectiveness: It is a economic technique since it requires fewer unit operations.
2. Stability: Direct compression is more suitable for moisture and heat sensitive APIs,
since it eliminates wetting and drying steps and increases the stability of active
ingredients.
3. Faster Dissolution: Disintegration or dissolution is the rate limiting step in
absorption in case of tablets with poorly soluble API prepared by wet granulation.

4. Wet granulation Dry granulation
In wet granulation, granules are formed by the addition of a granulation liquid onto a powder bed which is under the influence of an impeller (in a high-shear granulator), screws (in a twin screw granulator) or air (in a fluidized bed granulator). The agitation resulting in the system along with the wetting of the components within the formulation results in the aggregation of the primary powder particles to produce wet granules.
Dry granulation
The dry granulation process is used to form granules without using a liquid solution because the product granulated may be sensitive to moisture and heat. Forming granules without moisture requires compacting and densifying the powders. In this process the primary powder particles are aggregated under high pressure. Sweying granulator or a high-shear mixer-granulator can be used for the dry granulation.

6. Topic : Wurster Coating (Granulation Technology)
Subject (course): Biosciences Engineering and Allied (Pharmacy)
Topic : Wurster Coating (Granulation Technology)
Have anyone of you ever done a screencast for your class?
Yes
Learning Objectives:
(a) Receiving:
The student passively pays attention and get the topic in his memory and recognition which allows easy identification of topic from previous encounters or knowledge.
(b) Remembering/ Recall:
To retain in his memory by recalling facts, terms, basic concepts, and answers.
(c) Understanding
To perceive the meaning of the terms used; grasp the idea/ basic mechanism.
(d) Apply/ Organizing
To put together different values, information, mechanism discussed relating on what has been learned and probable question to be asked in in-class activity.

7. 4. Planning
Introduction of Wurster Coating
Advantages/ Limitations
Mechanism of granulation
Application of Wurster Coating

8. Introduction
Wurster coating is named after its inventor, Dr. Dale E. Wurster 
Wurster coating, synonymous with fluid bed microencapsulation.
It is the encapsulation of discrete particles in a fluidized bed using differential air flow to create a cyclic movement of material.
Principle:
Differential air streams move the bed of particulate upward in a cyclic motion inside the chamber as it is coated with an atomized material to create a core-shell structure.
GRANULATION MECHANISMS
To form granules, sufficiently strong bonds must be formed between powder particles so that they adhere and prevent breakdown of the granule to powder during handling.
There are four primary bonding mechanisms between particles:
Adhesion and cohesion forces in the immobile liquid films between individual primary powder particles.
2. Interfacial forces in mobile liquid films within the granules.
3. The formation of solid bridges after solvent evaporation.
4. Attractive forces between solid particles.

9. Advantages of Wurster Coating Limitations of Wurster Coating
Reduce moisture uptake
Control particle size
Improve flow
Achieve a uniform blend
Limitations of Wurster Coating
Increase in temperature may cause chemical degradation of thermolabile material.
Over wetting of granules can lead to large size lumps formation.

10. Mechanism of granulation
How it Works
Filler particles are loaded into the chamber and moved by the fluid bed in a cyclic pattern.
Spray nozzle at the bottom of the fluid bed atomizes the coating solution (solvent + coating material) and sprays concurrently with the moving particles.
Particles are suspended into the expansion chamber where the solvent evaporates and leaves behind the coating material

11. Spray pattern

12. Applications of Wurster Coating
Industry
Application
Pharmaceutical
- Coating drugs (prolong shelf life, masking odor/taste of drug)
- Control drug release in the body (delayed, enteric, sustained, extended etc.)
- Coating capsules
Food
- Mask certain flavors
- Improve stability and shelf life
- Extended release of flavors (e.g. gum)
Chemical
- Control release properties of chemicals
- Change absorption/surface properties
- Isolate active chemical in a mixture
Agricultural
- Coat seeds for easier handling (e.g. increase size for machine planting)
- Improve crop yields and/or germination by coating seeds with pesticides or nutrients.
Animal Feed
- Mask taste of products to improve palatability for animals
- Control release of product after ingestion
- Stabilize medicine by coating
Nutrition
- Optimize stability of an ingredient or product
- Control ingredient release properties