granulation Flashcards
what is a powder?
solid particles in the form of tiny loose particles
when used to describe a dosage describes a formulation in which a drug powder is mixed with other drug excipients to produce the final product
types of powders?
powders for external use
powders for internal use
powder for internal use?
oral powder eg antibiotic syrup (amoxicillin oral suspension)
powder for external use?
dusting powder eg. anti fungal powder ( clotrimazole powder)
what is a granule
a small grain
when powder particles have been agreggated to form a large particle
what do powders become when granulated
granules
what do powders become when sieved?
monosized granules
what do powders become when overmixing settling?
seggregated powder
why do we granulate powders?
to prevent seggregation
to improve flowing properties
to improve compaction properties
methods of granulation
dry granulation
wet granulation
what happens in dry granulation?
powders are mixed and compressed to form a slug
slug is then milled and sieved
what is dry granulation useful for?
used for api in powders that do not mix and compress well after wet granulation or are sensitive to granulation fluids (mainly water)
what happens in wet granulation
powders are dry blended and granulation fluid (with an adhesive binder) is added
wet granules are screened, sieved and dried
individual granules
what five primary mechanism make powders bonded together within granules
- adhesive and cohesive forces in immobile liquid film
- interfacial forces in the mobile liquid film
- solid bridges after solvent evaporation
- attractive forces (adhesive and cohesive) between solid particles
- mechanical interlocking
describe mechanical interlocking
particle size and shape will determine degree of interlocking
describe solid bridges
-partial melting
-hardening binders
-crystillisation of dissolved substances
describe the attractive forces (adehsive and cohesive) between solid particles?
in the absence of granulating fluid, two attractive forces exist between the solid particles:
electrostatic and van der waals
describe the adhesive and cohesive forces in the immobile liquid film
presence of a sufficient amount of liquid in a powder will result in a very thin layer of immobile layer (adhesive force)
distance between the particles reduces which increases the particle attraction due to the van der waals forces existing in the solid particles. (cohesive)
describe the interfacial forces in the mobile liquid film
addition of increasing amount of granulation fluid(mainly water) will produce a mobile film around all the particles.
what is one common application of wet granulation
multipartciulates-pellets or beads
what are the properties of multiparticulates
-small size
-sphercial shape
-narrow partcile
-low friability
-distributed throughout the gi tract
-high surface area/volume ratio
what is one common application of wet granulation
multiparticulates- beads and pellets
what are the properties of multiparticulates (beads and pellets)
high surface area to volume ratio
low friability
distributed throughout the gi tract
as spehrical as possible
small size
narrow particle
what is the effect of small size
what is wet granulation used to make
multiparticulate -pellets or beads
what is the advantage of pellets in the gi tract
contains high levels of active ingredient without using large particles
what are advantages of pellets
-controlled or immediate release
-can be filled into HGC’S or compacted into tablets to form unit dosage forms
-contains two or more active ingredients
can be coated at different coat weights to produce a range of release rates
what are the advantages of pellets in processing
