Powders 6 Flashcards
(27 cards)
What is granulation
process in which mixture of primary powder particle form larger, homogeneous multi particle entities called granules
why do we granulate
to improve
powder flow
compaction
to prevent
segregation
Describe the process of wet granulation
api and excipients are mixed and a wetting agent is introduced and a wet mass is formed. this is then reduced in size to form granules which are then dried and it proceeds on
describe the process of dry granulation
mixture is compressed between rollers to produce a sheet or flakes of material. these are then reduced in size by milling which are then sieved to separate the required fraction.
What are the advantages of wet granulation
relatively lower cost compared to dry granulation
combined purpose machines available
what are the disadvantages of wet granulation
multiple machines used, mixer, granulator, dryer
effects of drying times and temperature on drug stability
hydrolysis of drug
what are the advantages of dry granulation
can be used for materials sensitive to wetting
no drying
only one equipment
what are the disadvantages of dry granulation
can reduce the compaction properties of the granules
primary powder flowability problems can be observed
segregation of the mixture can occur
How does particle bonding work in wet granulation
adhesion and cohesion forces in immobile films cause inter particulate distance to decrease and increase the contact area where interfacial force in mobile liquid films which forms a solid bridge.
How does particle bonding work in dry granulation
attractive forces between solid particles form and solid bridges form
Describe the 4 steps of a shear granulator (wet granulation)
mixing of api + excip
formation of damp mass
granulation
drying
what are the disadvantages of a shear granulator
long duration
different equipment for each step
have been replaced by more efficient granulators
what is different about a high speed mixer
mixing wetting and granulator performed in one step
what are the disadvantage of high speed mixer
end point monitoring system required
describe the advantages of a fluidized bed granulator
all in one equipment
reduced labour cost
automation is possible
describe the disadvantages of a fluidized bed granulator
initial cost
large number of parameters which affect the granules
optimisation and automation lengthy process
describe the process of roller compaction
powder compressed between two rollers which have variable compression times. they then go to a oscillating granulator often used to break the sheet/ flakes to granules
what are the advantages of roller compaction
ecological and cost effective
relatively low investment cost
easy to scale up
what are the disadvantages of roller compaction
disadvantges not all materials respond well to roller compaction and may lose them in poor re compaction properties q
what is the main advantage of extrusion
incorporate high level of api in a relatively small particulates
describe the process of extrusion
mixing of the api + excips wet massing extrusion spheronisation screening
What is melt granulation
granulation process which uses a thermosetting material (hot melt bind) to bind the powder particles into granules
what are the advantages of melt granulation
no water or organic solvents used
what are the disadvantages of melt granulation
thermal degradation
not many alternatives to PEGS
