GRANULATION

By:Abdou K. AbdelrazigMohammed Ibrahim

Advanced methods of granulation:

These methods exploited the short comings of dry and wet granulation methods and paid more attention to the properties of materials being processed.They are:

1 -steam granulation.2 -melt granulation.

3 -Moisture activated dry granulation.4 -Foam granulation.

5 -Freeze granulation.6 -Thermal adhesion granulation

1 -Steam Granulation:

This process is a modification of the conventional wet granulation.

In this method steam is used as a binder instead of water.

The required amount of liquid is pumped as a form of steam.

Advantages of steam granulation:

1 -High distribution uniformity.2 -Higher diffusion rates into the powder.

3 -Steam granules are more spherical.4 -higher surface area and shorter

processing time.5 -Environmentally friendly .

Disadvantages of steam granulation:

1 -require special equipment for steam generation and transportation.

2 -Require higher energy input.

3 -not suitable for heat labile materials.

4 -more safety measurements are required .

2 -Melt granulation:In this process granulation is achieved by the addition of molten binder or a binder that melt during the process.The binder is solid at room temperature but it melts at temperature range of 50-80˚ C.There is no require for drying phase since dry granules are obtained by cooling it to the room temperature.

The process of granulation consist of three main steps:

1 -wetting and nucleation.Nucelation happens by two proposed mechanisms:Immersion and distribution.

2 -coalescence step.3 -attrition and breakage.

Meltable binders:It must be solid at room temperature and meltbetween 40 and 80°C.o Its physically and chemically stableo Its hydrophilic-lipophilic balance (HLB) to ensure thecorrect release of the active substance.o There are two type of Meltable binder

1 )Hydrophilic Meltable binders2 )Hydrophobic Meltable binder

Advantages and disadvantages of melt granulation:

-Heat sensitive materials are poor candidates

-Lower-melting-point binder may melt/ soften during handling and storage

-Higher-melting-point binders require high melting temp. and can contribute instability problems for heat-labile materials.

3 -Moisture activated dry granulation:

AGGLOMERATION

Advantages and disadvantages of MADG:

1 -It utilize less amount of granulating fluid.2 -Decreased drying time and produce

granules with excellent flow properties.3 -use less equipment.4 -lower tablet capping.

5 -no over or under granulation.#Disadvantages-:

Moisture sensitive and high moisture absorbing APIs are poor candidates.

Freeze granulation:Developed by the Swedish Ceramic Institute (SCI).

-By spraying a powder suspension into liquid nitrogen, the drops (granules) are instantaneously frozen. In a subsequent freeze-drying the granules are dried by sublimation of the ice without any segregation effects.

-Finally it produces spherical, free flowing granules.The granules size distribution will be controlled by the suspension rheology (flow properties) and process parameters (pump speed and air pressure).

Advantages of freeze granulation:

1 -control of granule density by controlling the solids content in the suspension.

2 -mild drying prevent serious oxidation of non-oxides and metals.

3 -no cavities in the granules.4 -low material waste and ease of cleaning of

equipment.5 -small and large granules quantities can be

produced to equal qualities.6 -possibility to recycle organic solvents .

Thermal adhesion granulation process:

This method is applicable in the preparation of direct tableting formulations.The process is preformed under low moisture or low content of pharmaceutically acceptable solvent.The process is done by subjecting a mixture of excipients and API to temperature range from 30˚C to 130˚C in a closed system under mixing by tumble rotation until the formation of granules.

-This method provides granules with:-Good flow properties.

-Binding capacity to form tablets with low friability.-Adequate hardness.

--Drying and milling to form the desired granules areunnecessary in the present invention due to the low

-amount of moisture introduced to the tableting mixture

Conclusion:All these methods together serve the purpose of enhancing the current methods of granulation used in pharmaceutical manufacturing.There are other methods that hadn’t been mentioned here that worth searching and knowing so go for it who knows you might find them interesting.These are:

-Granulex technology.-TOPO technology.

- -continueous flow technology.- -Pneumatic Dry Granulation.

References:Review article: recent advances in granulation technology by : Himanshu.K.Solanki*, Tarashankar Basuri, Jalaram H.Thakkar, Chirag A. Pateldepartment of Pharmacy, SSR College of Pharmacy, Sayli-silvassa Road, Sayli, UT of D& NH-396230, India.Published in International Journal of Pharmaceutical Sciences Review and Research on November-December 2010 issue

-A powerpoint presentation by Mr. NAMDEO SHINDESATARA COLLEGE OF PHARMACY, SATARA.About granulation .Aulton pharmaceutics.Handout of granulation.

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