Tablet Granulations

Granulation characteristics: The characteristics of a tablet that make it popular form (compactness, rapid production capacity, physical & chemical stability, efficacy etc) largely depends on the qualities of the granulation.There are many other formulation & process variables involved in granulation that should be considered to observer granulation suitability for tabletting:

1. Fluidity or flow properties: good flow properties are vital for the transportation of granules through the hopper, the feed frame and into the dies. Granules should therefore be in a form that flows smoothly and uniformly.The ideal physical form is spheres, since these offer minimum contact surfaces between themselves and with the walls of a machine.

Flow rate can be obtained by two common methods –

·        Repose of angle: A fixed funnel tip at a certain height, H and also with R, the radius of the base of conical pile:

o       tanα = H/R

·        Hopper flow rate: by this method, continually monitors the flow of granule out of conical hoppers onto a recording balance device.

2. Compressibility: another desirable characteristics, compressibility the property of forming a stable, compact mass when pressure is applied. Granulation compressibility is important because granulation is also a pharmaceutical process that controls a blend of powders which have poor cohesion.

3. Particle size and shape: known to affect the average tablet weight, disintegration time, friability, granulation flowability etc.

4. Surface area: determination of surface area of finely milled drug powders may be important for drugs that have limited water solubility, especially can have a significant effect upon dissolution rate.

5. Density: It may influence compressibility, tablet porosity, dissolution etc. Dense/hard granules may require higher compressible load to produce cohesive compact.

6. Strength & friability: A granule is an aggregation of component particles, that should held together by finite strength bonds.

7. Compaction: The process of consolidating and compacting power or granules to form a tablet.

 

Methods Of  Manufacturing Of  Tablet

There are three methods of manufacturing of tablets which may be use individually or combinely. The methods are:

·        Wet granulation

·        Dry granulation

·        Direct compression 
  
Tabletcoating processes