Make Granules Before Compression.

Granulation is an important step in tablet manufacturing.

Before the start of granulation, the production pharmacist must check the machines, equipment and surrounding area for proper cleaning as per GMP.

After satisfaction, the production pharmacist signs the line clearance sheet and is then countersigned by the quality assurance officer on a random basis.

Line clearance is permission to start the granulation operation.

Granulation can be divided into three types based on the formulation.

1. Direct compression.

2. Dry granulation 

3. wet granulation.

Detail about all the above categories is as under;

1. Direct compression.

In this process, the formulation consists of material already containing granules property I.e, crystalline materials like sodium chloride, sodium bromide or potassium chloride may be directly compressed to form tablets.

To avoid flow and other material properties causing hindrances, we have to mix the drug, filler, lubricant, glidant and the disintegrating agent in a blender and then directly loaded into the compression machine for tablet compression.

Why do we choose direct compression?

As said earlier granulation depends upon the formula and then the formula depends upon the nature of the active component or components which decides the type of granulation to be decided.

When the active component is heat or moisture sensitive, it will deteriorate if we choose wet granulation where heat and moisture are compulsory.

This is why we are bound to adopt the direct compression method.

In direct compression, consider other factors in the formula like the availability of the active drug after the disintegration, flow of powder etc before operation.

Direct compression material should have good flow properties and must be inert, tasteless and able to disintegrate.

2. Compression granulation.

It is also called dry granulation. This type of granulation occurs due to the following reasons;

1. when the percentage of active ingredients is too much in the formula.

2. substance is sensitive to moisture and heat 

3. For Example, Aspirin and vitamins are granulated by this method.

4. Large-scale manufacturing needs a compression machine with two compact rollers(For pre-compression) which revolve over each other( before passing through the main rollers) to pre-compress the tablets before final compression within the machine.

While on a small scale drug along with additives and lubricants is mixed together and then compressed(Process is called pre-compression) for the formation of tablets and then the compressed tablets are crushed(the process is called comminution or slugging), sieved, mixed again along with lubricants, glidants disintegrating agent and then again loaded to the machine to get the final compressed tablets with all the specifications as per  BMR.

3. Wet granulation.

Wet granulation is suitable for those drugs which are heat and moisture-resistant.

In this case, active ingredients and additives are mixed in a mixer and then a solution of self-adhesive(prepared in water or liquid) is added and again mixed in a granulator for a certain time mentioned in BMR.

The wet mass is then passed through a hammer mill for getting granulated mass which is then dried in the dryer. 

Dried lumps are crushed through a crushing mill, sieved and then mixed in a blender along with glidant, lubricant and disintegration agent as per the formula. finally, granules are obtained with good flow properties.

Granules are then shifted to a compression machine for tablet compression.

Reasons for granulation:

1. To prevent segregation of powder particles.

2. Ideal granule will surely constitute all ingredients as per proportion.

3. Improve the compression characteristics of the mixture.

4. To reduce the toxicity of drugs.

5. Improve the flow property required for the proper formation of the tablet.