tabletting part 3 Flashcards
what is the function of bulking agents?
‘making tablets that are big enough to swallow and handle’
common examples of bulking agents?
sugars, sugar alcohols, minerals, polymers, Spray Dried Lactose, Lactose monohydrate - crystalline
what are desirable characteristics of bulking agents?
good compactability
good flow
chemically compactable with drug
inexpensive
available in different grades of size and shapes
what does good compactability mean?
strong tablets formed at low pressures
what is required for good flowing tabelts?
particles that are round
what is spray dried lactose good for?
compresses really well because it has anhydrous lactose
good for direct compression
large crystals give good flowability
properties of lactose monohydrate-crystalline?
poor compressibility
good for wet granulation because with large crystals it takes longer to dissolve so more control over the end point of the granulation
what is the function of compression aids?
to make tablet stronger when particles don’t compact well
common example of compression aid?
Microcrystalline cellulose (MCC)
desirable characteristics of compression aids?
‘compactable
plastically deforms so maximised bonding inside tablet’
what is cellulose?
linear polymer of glucose
what is the function of an disintegrant?
makes the break up of tablets faster when exposed to fluids and releases drug particles
what is starch?
swelling disintregrant
how is starch a disintegrant?
OH groups to attach to water
what is a polymorph?
crystalline forms of drugs
what are the disadvantages of lactose?
you need a compression aid present with other tablets that are poorly compressible
lubricants weaken bonding
causes browning of tablets with the aldehyde group
disadvantages of MCC
more expensive than bulking agents
hygroscopic so has to be stored in a dry place
if damp it doesn’t flow well
properties of of MCC?
‘chains that are stacked into orderly manner
under pressure the chain slips and it has a plastic behaviour’
examples of disintegrants?
MCC, starch
disadvantages of disintegrants?
elastic- tablets are made weaker
what are the mechanisms for disintegrants?
swelling-swells causing tablet to burst
wicking- water drawn in through fibres
effervescent- co2 produced
what is MCC?
wicking disintegrant
properties of MCC?
cellulose fibres
properties of super disintegrant?
they attract water
cellulose polysaccharide chain
crosslink limits swelling forming an insoluble sponge
example of superdisintegrant?
sodium croscarmellose
what is the function of a lubricant?
makes sure tablet is ejected out of the die with limited friction
common examples of lubricants?
magnesium stearate
SDS
stearic acid
disadvantages with magnesium stearate?
hydrophobic so when rubbed over other particles it makes them water repellent which decreases drug dissolution
weakens inter-particulate bonding so weaker tablets
so mixed for a short time
SDS can be an alternative but not as effective
structure of lubricants?
long hydrocarbon chains
stacks of flat waxy crystals so easy to slide over each other
function of flow aids?
increases flowability
examples of flow aids?
colloidal silicon dioxide
structure and function of flow aids?
smaller than other excipients in size
coats surfaces of particles and absorbs moisture so they don’t stick
disadvantages of flow aids?
dust hazard
types of tablets?
dispersible
immediate release
delayed release
extended release
tablets for special use
diagram of how dispersible tablets work?
slide 17
where is the absorption of most drugs?
upper small intestine by duodenum and jejunum
how are duodenum and jejunum adapted for absorption?
have vili on their surface increasing surface area
requirements for tablets hat rapidly dissolve in saliva?
‘palatable
rapid disintegration in mouth
flat
thin
porous to maximise surface area for dissolving’
what is included in the formulation design?
soluble bulking agents
wetting agents
flavours
disintegrants
solubility enhancers
what considerations required for the packing of tablets that rapidly dissolve in saliva?
water proof pack so double aluminium foil because its hygroscopic
requirements for effervescent tablets?
should disintegrate rapidly
palatable
big tablet so it isn’t directly swallowed
what is the formulation design for effervescent tablets?
soluble bulking agents
wetting agents
solubility enhancers
flavours
pack considerations for effervescent tablets?
hygroscopic so pack has to be waterproof
requirements for chewable tablets?
bigger than usual
flat- chewable
palatable
formulation design for chewable tablets?
flavours
sweeteners
immediate release tablets
what are the requirements for packaging of chewable tablets?
hygroscopic so water proof package with double aluminium foil
what are chewable tablets use for?
drugs that need large doses and don’t taste too bad
small dose drugs formulated into chewable tablets
what are the requirements for lozenges?
dissolve slowly in the mouth
palatable
formulation design for lozenges?
compressed powder tablets
sweeteners
no disintegrant
no wetting agents
as for immediate release tablets
requirements for lozenges packaging?
as for immediate release tablets
what are lozenges used for?
sore throat
how are immediate release tablets dissolved into the bloodstream?
‘swallowed
coating dissolves
disintegrant absorbs stomach juices and the tablet swells
disintegration happens
dissolution occurs
drug is in solution now and is absorbed’
what are the requirements for IR tablets?
should disintegrate in stomach
size that can be swallowed
palatable (taste masking)
what is the formulation design for IR tablet?
bulking agents
compression aid
disintegrant
flow aid
binder
lubricant
what is the pack requirement for IR tablets?
hygroscopic
what is the point of packaging?
designed to protect tablet
what are the three blister packages?
transparent plastic
semi-transparent
double aluminum foil
requirements for delayed release tablets?
remains in tact and no drug released in the stomach
disintegrates rapidly in neutral ph of upper intestine
what is the formulation design for delayed release tablets?
polymer coating that is gastro-resistant
as for immediate release
what is the packaging for delayed release tablets?
hygroscopic
what are DR tablets used for?
to protect stomach form irritation causes by drug
to protect tablet against stomach acid
how are DR tablets absorbed?
‘tablet swallowed
coating is resistant to stomach acid so tablet passed through
polymer coat ionises and dissolves at intestinal ph
tablet disintegrant and releases the entire dose’
requirements for extended release tablets?
gradual release of drug
drug release should continue in all conditions of GI tract
dose shouldn’t be release at once
should contain enough drug to be released gradually over a long time
what is the formulation design of the extended release drug?
coated or matrix coated
no disintegrant
packaging for extended release tablets?
hygroscopic
what are extended release tablets used for?
for daily dosing a few time with short half-life
for prolonged therapy
how are extended release coated tablets absorbed in the body?
tablet swallowed
the coating controls rate of release of drug
no disintegration
drug released slowly through transport in the GI tract
all drug is slowly released
what are the different coatings for an extended release tablet?
diffusion barrier coating
phase separate diffusion barrier coat
phase separated porous coat
how does diffusion barrier coating work?
release of drug controlled by diffusion through permeable coat
how does phase separated diffusion barrier coat work?
drug diffuses through one component of the coat
how does phase separated porous coat work?
drug released through holes in the coating when component is dissolved
what is the rate controlling factor when drug is diffusing?
water
how are extended release matrix tablets absorbed in the body?
tablet swallowed
matrix material controls the rate of release of drug and drug released slowly through GI tract
most matrix gradually erode through the GI tract
difference types of matrix?
inert matrix at low drug loading
inert matrix at high drug loading
hydrophilic matrix
wax matrix
what is inert matrix low drug loading?
when drug is released by diffusion through matrix
what is inert matrix at high drug loading?
drug released through percolation channels
what is hydrophilic matrix?
polymer in tablet hydrates forming gel layer
(a surface diffusion barrier)
drug released via diffusion through this layer
what is wax matrix?
surface erodes as it goes through GI tract and particles dissolve when they’ve reached the surface
requirements vaginal tablets?
release drug in vagina
shaped for easy insertion
formulation of vaginal tablets?
hygroscopic
what are vaginal tablets?
local effects only
requirements buccal and Sublingual Tablets and Lozenges?
drug release in mouth
if immediate release-should dissolve quickly
if extended release- retained for a long time
what is the formulation design?
for immediate release:
dispersible tablets-very fast release
immediate release
lozenges
for extended release:
as hydrophilic matrix
mucoadhesive
what is the packaging for lozenges?
hygroscopic
what are Buccal and Sublingual Tablets and Lozenges used for?
local effect- mouth ulcer
systematic effect- angina relief
