Tabletting Flashcards
what are tablets
single dose of compressed powder
why are tablets good
small, stable (no water and coating blocks light) , easy to identify with its colour/shape, taste masked by coating, packaging can be made water resistant
common shapes of tablets
round, oval, capsule
flat, bevelled, convex
name the stages of tablet manufacturing process
powder mixture of drug and excipients, wet/dry granulation then granules or direct compression, basing, compression into tablets, de-dusting, tablet coating, packing
what is basing
dry mixing in lubricant and more disintegrant if needed
list the 3 batch sizes
lab scale- formulation design stage
pilot scale- clinical trials
full scale industrial batch
what are excipients
inactive ingredient in drugs
what is the aim of a powder mixture
uniformly mixed, flows well, doesnt separate
what processes can cause powder separation and how
-transport, mixing, tablet machine vibration
-causes smaller particles to fall through the spaces between the bigger ones
-caused by difference in particle shape size and density
consequences of separation
variability in dosage which can lead to under or overdosing, uneven distribution of drug/excipients eg. some parts of the drug will have more disintegrant so it will be released faster than others
what is the aim of granulation (powder binded together forms granules)
prevent powder separation
describe wet granulation and its variables (know the diagram)
bowl, detector probe, rotating impeller and chopper, solution of binding agent sprayed onto powder, wet granules are dried then sieved
variables- mixing time, rate of adding liquid, speed of impeller and chopper, internal environments
stages of granule formation
- wetting and nucleation- small aggregates form from particles
- consolidation and coalescence- granules grow as aggregates combine
limits to granule growth- amount of fluid, breakage, attrition
how to detect granulation end point
trials or detector probes
what happens if you stop before the granulation end point
aggregates are under-wet, too fragile for drying process
what happens if you stop after the granulation end point
aggregates are over-wet, dry lumps are hard to compress
what is granulation end point
maximum amount of good granules
describe dry granulation (ribbon type) and its variables
hopper, screw feeder to ensure constant supply, powder is compacted between roles producing ribbons of compressed powder, ribbons are broken up then sieved to make granules
variables- feed rate, roller speed, moisture content of powder
difference between granules formed from wet and dry granulation
wet- particles glued together with binding agent (water soluble polymer)
dry-particles held by compression at points of contact
advantages and disadvantages of direct compression
advantages- saves money (no granulation equipment), saves energy, saves time, faster development time and less processes
disadvantages- mixture must flow, powder mix cant segregate, needs special excipients, hard on industrial scales
how are tablets compressed
using a rotary press or die and lower/upper punches
granule requirements for a good tablet to be formed
good flow- large round particle, fills die accurately to make uniform weight and dose
compactable powder mix- lots of inter particulate bonding, produces strong tablets, prevents capping/breaking
no separation- ensure composition of tablet stays the same, prevents deficiency in one component
right amount of lube- tablets can be ejected with minimum force, prevents them breaking due to high ejection pressure, too much can lead to weak tablets, machines struggles to eject if too little
why do tablets need the right amount of lubrication
to ensure tablets are ejected with minimum force, too much can break the tablets due to high ejection pressure, too little can be hard to eject, too much will have too little interparticulate bonds and form weak tablets
