Tablets Flashcards
What are the advantages of tablets?
- Dose accuracy
- Stability
- Pt acceptance
- Diff techniques to control drug release
What are the disadvantages of tablets?
- Irritation of GI mucosa
ex: esophageal ulceration - Pt’s w/ GERD
- Elderly (chewable or liquid form)
How to prepare tablets w/ molding?
- shaping & hardening of semi-solid mixture of drug & excipients using “tablet mold”
- it’s restricted for small-dose tablet & for small scale production
How to prepare tablets w/ compression?
- Filling
- Metering
- Compression
- Ejection
What is granulation?
Poor flow of powders
Need: fluidity & compressibility
1. Spherical shape
2. Normal distribution of particle sizes
3. Homogenous distribution of ingredients
4. Acceptable compression & disintegration properties
What are diluents/fillers?
add the necessary bulk to a formulation to prepare tablets of the desired size
for potent drugs
ex: Lactose
What are binders?
promote adhesion of the particles to form granules & maintaining the integrity of the final tablet
sugars & polymers freq. added as solutions or slurries to powdered material
ex: Starch, Gelatin, PVP, CMV
What are lubricants?
ease of the ejection of the tablet from the die
prevent filling material from sticking to the punches & dies
reduce wear on the tooling
they are applied to coat granules therefore particle size of lubricant is imp. for uniform coating
ex: Magnesium stearate (+SLS)
What are disintegrants?
promote tablet breakup after admin to granules then to smaller particles for ready drug avail.
reverse effects of the binder & compression forces
disintegrate may be external or internal
ex: Starch, Cellulose derivatives, Mix of bicarb & organic acid
What are glidants?
used to improve flowability in direct compression
function by reducing friction b/t particles or reducing buildup of static charge
enhance the flow of the material into the tablet dies
generally, also have some lubricating property
ex: talc & silicone dioxide
What are the 3 tablet manufacturing techniques?
- Direct compression
- Dry granulation
- Wet granulation
Compression:
process of pressing material to make it more firm & solid
reduction in the bulk volume by elimination of air
Consolidation:
increase in mechanical strength of the mass due to particle/particle interactions (bond formation)
on decompression some of the bonds formed break due to elasticity
- if sufficient bonds remain, a tablet is formed
Sticking:
- inadequate lubrication
- granules too dry or wet dirty or scratched die
- worn die
Picking:
- inadequate lubrication
- granules under-dried
- scratched or damaged punch face
Capping:
- too fast compression speed
- worn tooling
- excessive pressure
- excess fines
- insufficient or ineffective binder
- over-dried granules
Content uniformity:
ALL tablets must contain 85-115% of the drug & RSD <6%
Weight uniformity:
uncoated tablets, drug > 50 mg & drug > 50% of total weight
Disintegration test:
time req. for a tablet to disintegrate in a specified test fluid at a specified temp
if 1 or 2 tablets fail, more 12 tablets are tested. <2 of the 18 tablets fail
Dissolution test:
time req. for a tablet to dissolve in a specified test fluid at a specified temp
Friability test:
measure of tablet resistance to abrasion
used to assess how a tablet will withstand handing & general wear & tear
Tablet breaking force:
force req. to break the tablet at a specific plane (ex: diameter for round tablet)
to determine the ability of a tablet to withstand shocks during handling & shipping
also correlates w/ disintegration & dissolution
Applying a coating layer on the tablet core:
- Controlling drug release
- Taste or odour masking
- Physical & chemical protection
- Protecting the drug from the gastric environment
What are the various techniques for tablet coating:
- Sugar coating
- Film coating
- Enteric coating
Sugar-coating:
- water soluble coating quickly dissolves after swallowing
- protects the drug from the environment
- provides a barrier to objectionable taste or odour
- permits imprinting of identifying manufacturer’s info
What is the downside of sugar-coating?
- may add 50% to the weight of the uncoated tablet
- increase in size, weight, & shipping costs
- the time & expertise req. in the coating process (sealing, subcoating, syruping, finishing & polishing)
What is Film coating?
using one or more film forming polymers capable of forming a skin-like film on the surface of the tablet
What are the advantages of film coating over sugar coating?
- more durable, less bulky
- usually film represents less than 5% of the finished tablet weight
- film coating may be enteric or non-enteric in nature
- less time-consuming to apply
What is the criteria of a film forming material?
- soluble in solvent suitable for process
- soluble in GI fluids
- forms a strong continuous film which is smooth & elegant
- stable to heat, light, air, moisture, & compatible w/ the drug in the product
- have no appreciable taste, odour, or colour
- able to support pigment or coating additives
- non-toxic
- crack resistant (usually by inclusion of additive)
What is the film coating formula?
- Non-enteric coating material: usually are cellulose
- Enteric material: usually phthalate esters of cellulose
- it’s common to use a mixture of materials to give a film w/ the desired properties
- a plasticizer is included to prevent the film from chipping
- mixture of solvents to control evaporation
- colouring agents
