2. DRY GRANULATION PROCESSDRY GRANULATION PROCESS
• Dry granulation may be used if the materials have sufficient inherent binding or cohesive
properties to form granules.
• Dry granulation refers to the process of granulating without the use of liquids.
• There are two dry granulation methods used in the pharma industry: slugging and roll
Drug A d ju v a n t
S c r e e n
Blend Pellet G r i n d
L u b r i c a n t s C
Tablet B l e n d
C o m p r e s s
DRY GRANULATION PROCESS SCHEMATIC DIAGRAMDRY GRANULATION PROCESS SCHEMATIC DIAGRAM
3. Slugging (Old Method)Slugging (Old Method)
• material to be granulized is first made
into a large compressed mass or "slug"
typically by way of a tablet press using
large flat-faced tooling.
Disadvantages of SluggingDisadvantages of Slugging
• single batch processing
• frequent maintenance changeover
• poor process control
• poor economies of scale
• low manufacturing output per hour
• excessive air and sound pollution,
• increased use of storage
• more energy and time required to
produce 1 Kg of slugs than 1 Kg of
Aspirin SluggingAspirin Slugging
Slugging Tablet Press (Tablet Press Company)Slugging Tablet Press (Tablet Press Company)
4. • material particles are
consolidated and densified by
passing the material between
two high-pressure rollers.
• densified material from a roller
compactor is then reduced to a
uniform granule size by milling.
• capable of handling a large amount
of material in a short period of
• Invented by Francis Xavier Chilson
Roller Compactor / Chilsonator (New Method)Roller Compactor / Chilsonator (New Method)
6. Roller OrientationRoller Orientation
A. Horizontal orientation
In horizontal roll orientation the loss of material due to bypass is high as compared to other designs
B. Vertical orientation
Loss of un-compacted material is minimal in vertical orientation due to independence of feed to gravitational forces
C. Incline orientation (position between horizontal and vertical)
The use of inclined roll orientation decreases bypass from 15-20% to 7%
1: Filling hopper, 2: Feeding auger/screw feeder, 2’: Screw feeder, 3: Tamping auger, 4:
Rolls, 5: Flake crusher, 6: Granulator, 7 and 8: Two stage diagonal granulation system using coarse and fine granulator,
• The roll orientation plays significant role in generation and minimization of bypass.
7. Variables of Roller CompactionVariables of Roller Compaction
• In the slip or entry region powder starts to move but
at a speed slower than the roll speed, thus indicating
that slips occur therefore termed “slips”.
• The nip region starts at a roll angle α, (nip angle),
when the wall velocity of the powder becomes equal
to that of the rolls.
• The release region starts when the roll gap starts to
increase again and its size depends on the
stored elastic strains in the compact, release rate
of compact,t and the roll speed.
Schematic of the main regions during roller compactionSchematic of the main regions during roller compaction
horizontal/vertical feed screw
8. Requirements for Roller CompactionRequirements for Roller Compaction
• adequate supply of the powder to the nip region and entire conveying of
powder entering from nip region into the narrowest part of the roll gap.
• uniform distribution of the compaction pressure over the whole roll-gripped
• adequate, effective, and uniform de-aeration of powder mass via vacuum
before it reaches the nip region.
• material to be processed should be compressible, should have consistent
increase in density with force, suitable for milling operation and
9. Advantages of dry granulation:Advantages of dry granulation:
• Useful for heat or moisture sensitive materials.
• Less equipment and space than that required by wet granulation.
• Improve tablet disintegration since it does not involve the use of water so it increases water-uptake ability of
• This method is of value in the production of certain dosage forms as effervescent tablets.
Disdvantages of dry granulation:Disdvantages of dry granulation:
•Requires high duty machine if compared with direct compaction
•Since it is dry process, more dust is produced which may contaminate other drug
In my opinion:In my opinion:
I prefer dry granulation because it is:I prefer dry granulation because it is:
•use less spaceuse less space
•it eliminates addition of moisture and heat which contributes to the product’s degradationit eliminates addition of moisture and heat which contributes to the product’s degradation
•Mechanical strength of the product in more uniformMechanical strength of the product in more uniform
•Machine is easy to maintain after operationMachine is easy to maintain after operation
When to Use Dry Granulation?When to Use Dry Granulation?
• this method is used when direct compression is not applicable (e.g., large-dose or poor compressibility
• when wet granulation cannot be used (e.g., drugs sensitive to heat or moisture).
• Vitamins and effervescent tablets are examples of products prepared by dry granulation.
11. Text References:
• Miller RW. Roller Compaction Technology. In: Handbook of Pharmaceutical Granulation
Technology, Parikh, Marcel Dekker Inc., New York, 1997: 81, 99-150.
• Teng Y, Qiu Z and Wen H. Systematical Approach of Formulation and Process Development
Using Roller Compaction. Eur. J Pharm Sci 2009; 73(2): 219-229.
• Kleinebudde P. Roll Compaction/Dry granulation: Pharmaceutical Applications.Eur J Pharm
Biopharm 2004; 58; 317-326.
• Hariharan M, Wowchuk C, Nkansah P, Gupta VK. Effect of Formulation Composition on the
Properties of Controlled Release Tablets Prepared by Roller Compaction. Drug Dev’t. Ind Pharm
2004; 30: 565-572.
• Funakoshi Y, Asogawa TSE. The Use of a Novel Roller Compactor with a Concave-convex Roller
Pair to Obtain Uniform Compacting Pressure. Drug Dev Ind Pharm1977; 3: 555-573
• Bozic DZ, Dreu Rand Vrecer F. Influence of Dry Granulation on Compactibility and Capping
Tendency of Macrolide Antibiotic Formulation. Int J Pharm 2008; 357: 44-54.
Video and Picture Attachments:
• Internet Google Images
• You Tube – Animation Video Dry Granulation Process