oral powders and tablets Flashcards
how are tablet forms more convenient for the manufacturer
- more stable than liquid
- easy to scale up
- versatile machinery
why are tablets convenient for the patient
- accurate dosage
- easy to take
- easy to carry
- release rate can be controlled
what has to happen to products with low flowability before they can be made into tablets
they have to go through the granulation process
what are excipients
they are pharmacologically inert materials that are added to pharmaceutical dosage characteristics.
can excipients affect the bioavailability of the active ingredient
they might
can excipients be swapped around
no, they are biologically inert
what does bio inert mean
it doesn’t invoke a response or interact with biological tissue
what are fillers (aka dilutents) used for
to add the necessary bulk
what is the min weight a tablet must be
over 50mg
common water soluble fillers
lactose
glucose
mannitol
common water insoluble fillers
cellulose
what do binders (aka adhesions) do
promote adhesion of the particles
examples of solution binders
- starch
- sucrose
- gelatin
- PVP
- cellulose derivatives
dry binder examples
microcrystalline cellulose
what do glidants do
they improve flowability and reduce friction between particles
glidant examples
- colloidal silica
- talc
what do lubricants do
they reduce the friction between the particles and the die wall and makes sure they don’t stick during compression process
examples of lubricants
- fluid lubricant
- magnesium stearate
how does magnesium stearate work
it has a hydrophobic tail which coats the particles and makes sure they don’t stick to surfaces
can magnesium stearate change the properties of a tablet
yes and can make it take longer for them to dissolve
what do disintegrants do
they promote breakage into smaller particles after administration
examples of disintegrants
starch
how do disintegrants work
they expand when exposed to water and pushes the tablet apart
other excipients
- colourants
- flavouring agents
- sorbents
what are sorbents
compounds which absorb water meaning it prevents hydrolysis or delays it
what are the three steps of tablet formation
- filling
- compression
- ejection
what happens on decompression when using elastic material compared to plastic
elastic material will expand whereas plastic material will not
what effect does compression have on the content
- pores number decreases
- pores size decreases
- mechanical strength of the compressed mass increases
- tendency of the compressed mass to disaggregate decreases
what happens during compression
- repacking of particles
- elastic or plastic deformations
- powder or granule fragmentation and formation of new surfaces
- cohesion between particles
- elastic or plastic deformation of the solid mass
- tablet ejection
advantages of uncoated tablets
they’re cheap and easy to make
advantages of coated tablets
easy to swallow
what do effervescent tablets contain
bicarbonate and citrate to dissolve
advantages of modified release tablets
they control how and at what rate disintegration occurs
what are the types of tablet coatings
- sugar coating
- film coating
- press coating
what are the steps to sugar coating
- sealing of tablet cores
- subcoating
- smoothing
- colouring
- polishing
- printing (optional step)
advantages of film coating to sugar coating
- less volume increase
- better stability of the tablet
- better mechanical strength
- one step process
what does coating suspension contain
- polymer, ethers of cellulose, other polymers
- plasticisers (PEG, oils)
- colourants (iron exide etc)
- solvents (used to be organic, now usually water)
what is a gastro-resistant coating
a polymer coating that disintegrates/dissolves at a pre-determined trigger
why would a gastro-resistant coating be used
some drugs dissolve too quickly in the stomach and patients can’t actually get the drug
advantages of gastro-resistant coating
- protect stomach from drug (NSAIDS)
- protect acid sensitive drugs
how does gastro-resistant coating work
carboxylic acids at low pH are unionised, when pH increases they become ionised and being to dissolve
why can’t you crush gastro-resistant coating drugs
it removes the enteric coating and the drug will dissolve fully in the stomach
challenges of gastro-resistant drug
the pH of the GI tract is not always predictable
what is colonic targeting used for
to ensure drug breaks down in the colon
how does colonic targeting coating work
bacteria in the gut breaks down the coating and allows the tablet to break down
challenges in colonic targeting coating
if the patient has issues with their gut microbiome, the bacteria needed to break down the tablet may not be there
examples of ingredients in colonic targeting coating
ethylcellulose, resistant starches
