Pharmaceutics Flashcards
Describe sugar coated tablets
Multiple layers at least 15 sugars applied
tablet must be round
explain the process of tablet manufacturing
- ) powder/granule must be mixed well
- ) powder/granule must flow well from hopper to press
- ) powder/granule must not separate between hopper and press
- ) powder/granule must be compressed into tablets
- ) tablets must withstand further treatment e.g. coating, packaging, transport
what are constituents of tablets?
- ) drug
- ) Diluent e.g. lactose monohydrate
- ) compression aid e.g. Microcrystalline cellulose
- ) Binder e.g. PVP
- ) Disintegrant e.g. Pregelatinised starch
- ) Lubricant e.g. Magnesium stearate
- ) Glidant e.g. talc
- ) Colour and flavouring
- ) Acidity regulator e.g citric acid
- ) surfactant to improve dissolution
What are formulation techniques for tablet?
- ) Direct compression
- ) Wet granulation
- ) Dry Granulation
- ) Roller compaction
summarise direct compression technique
mix the drug and excipients
lubricate the powder mix
compress into tablets
low shear mixing equipment needed (cheap)
in direct compression why do all excipients need to be spray dried except the lubricant?
to ensure sphericity
to improve mixing
to improve flow characteristics
give an example of a disintegrant
pregelanitised starch
give an example of a compression aid
microcrystalline cellulose
give examples of lubricants
magnesium stearate
stearic acid
sodium stearyl fumarate
give examples of diluents
lactose monohydrate
dibasic calcium phosphate
mannitol - cool taste
sorbitol - non-sugar
what bonds holds the tablet together?
non-covalent adhesive forces between the particles van der waals, london.
compression characteristic - brittle fracture what does it increase?
brittle fracture increases total particulate surface area
produces stronger tablets
compression characteristic - plastic deformation
it doesnt increase surface area
produces weaker tablets
no dissolution problems
powder compressed into tabs
tabs remain intact when pressure is applied
particles elastically return back to original state once pressure is not there
which constituents show brittle fracture
lactose monohydrate
dibasic calcium phosphate
which type of compression characteristic does microcrystalline cellulose?
Elastic Deformation
describe ordered mix
small drug particles adhered to larger carrier particles
used in dry powder inhales
not used in tabletting
advantages of direct compression
quickest method lowest time and labour cost no heat involved no water/solvents involved lubrication done in same vessel as mixing-reduces transfer loss
disadvantages of direct compression
more expensive excipients required
relies on drug being easily mixed
segregation issues due to vibration
describe wet granulation technique
- ) dry mix the drug/powder
- ) add granulation fluid to mixed powder to form wet granules
- ) dry the wet granules- remove liquid keep granule structure
- ) mill the dried granule to remove large lumps
- ) lubricate the milled granule
- ) compress into tablets
what is an example of super disintegrant
sodium starch glycollate
croscarmellose
what is an example of granulation fluid
water
ethanol
what holds the granules together in Wet Granulation?
solid bridges from wet binders e.g. PVP
NON-covalent adhesive forces e.g. van der waals, london forces by INTRA-GRANULARLY
What happens when there is too much granulation fluid?
overwetted granule which will result in dissolution of the granule
wet granulation- End point detection
Stop the process periodically and squeeze the granule
• Granule should feel slightly damp, not wet or soggy
• Granule should hold together after squeezing (like a cake)
• Should be able to “snap” granule block in two
• Old-fashioned method
• Difficult to feel texture of granule through gloves, but
often the only method applicable on a very small scale
• Can’t do this on production scale with enclosed equipment
if a tablet has low solubility and is very strong which distegrant should you use
superdisintegrant to speed tablet disintegration
Advantages of Wet granulation?
reduces mixing and segregation issues
best for low dose drugs
film coating is way easier compared in direct compression
Wet granulation is the choice always if possible
Disadvantages of Wet Granulation
more steps than direct compression
more chance of things going wrong
water/solvents needed which is not good for water sensetive drugs
heat required
Explain the process of Dry Granulation
Mix the drug and excipients compress to form large tablets more than 1 diameter Mill the tablets to produce dry granules lubricate granule if needed compress into tablets
advantages of dry granulation
no heat or solvents used
cost effective
disadvantages of dry granulation
may have powder flow issues
more processing steps needed
final tablet softer compared to wet granulated tablet
explain the process of Roller compaction (Chilsonation)
Mix the drug and its excipients compress powder mix between two rollers to produce ribbon mill the ribbon to produce dry granule lubricate if needed compress into tablets COMPLEX!
advantages of roller compaction
cost effective
no heat or solvents used
disadvantages of roller compaction
specialised equipment required
might have powder flow issues
softer tablets produces
dusty operation
