MDM: Tablets Flashcards
What are tablets?
A solid preparation manufactured by compressing uniform volumes of particles which contain a single dose of one of more active ingredients and excipients.
What are advantages of tablets?
- Convient - to carry/ store
- Good patinet compliance
- Acurate dosing
- chemical, physical and microbial stability
- Generally cheap, robust and elegent
Disadvantages of tablets
- Generally systemic delivery
- poor bioavailability
- must be swallowed
- local irritation - GI mucosa
- Extensive developmental work
What are the basic steps taken when forming a tablet?

When forming a tablet what are the ideal properties for a powder blend?
- Homogenous - doesn’t segregate
- Free flowing - freely flows through tablet machinary
- Adheres and coheres
- doesnt adhere to tablet tooling
What are examples of excipents included in tablets?
- Binder
- Distigrant
- Lubricant
- Diluent
- Glidant
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What is the role of a diluent and some examples?
Increases tablets bulk density and acheive required strength
Lactose, sucrose, mannitol, glucose, Calcium hydrogen phosphate, MCC
What are examples of lubricants and their role
Reduce friction between tablet and machinary during manufacture
Magnesium sterate and sodium steryl fumarate
What are examples of binders and their roles
Improves mechanical strength by binding particles
PVP, gelatine, sucrose
What is the role of distigrants and some examples
Promote rapid tablet distigrant
Starch, cellulose, PVP,
What are example of glidants and their roles?
Improves powder flow by reducing intra-particular friction
silica, magnesuim sterate, talc
What are methods used to determine powder flow?
What do these methods tell you?
- Flow through an orfice - flow rate
- Angle of response - inter particular cohesion
- Bulk density - percentage compressability and friction
What is powder flow dependent upon?
- Particle size, shape and density
A powder has poor flow characteristics. What could be done to sort this?
- Increase particle size and reduce size distribution
- Change particle size and texture e.g. during spray drying, cyrstallisation
- Change surface forces - e.g. add glidant
- Alter process conditions e.g. vibration assisted hoppers
What are examples of equipments used to mix powders?
- tumbling
- high speed mixer granulators
- fluidised bed mixers
- agitator mixers
What is powder mixing depent on?
- shape
- size
- density of particles
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What improvement could be done to improve powder mixing?
- Granulation
- Reduce particle size distribution - e.g. sieving or milling
- controlled crystilisation - particular shape and sized crystals
- Choose excipents with similar density to API
- Reduce blending movement
- Equipment - reduce time in hoppers, reduce transfer
When forming tablets what are the 2 methods that can be used?
Describe breifely these
Direct compression - drug and excipents mixed
or granulation - primary powder particles adhere to form granules
What are advantages and disadvantages of direct compression?
Advantages:
- Faster drug dissolution
- Reduction in manufactuing time and costs
Disadvantages:
- powder segregation
- poor compaction properties
- poor colour uniformity
- specialist fillers and binders required
- powder must have good flow properties
Advantages and disadvantages of granulation
Advantages:
- increases compactiabilty
- improved colour uniformity
- improves powder flow
- increases bulk density
- improves homogeneity and prevent segregation
Disadvantages:
- increases in production time and costs
- may cause hydrolysis of drug
Describe 2 other granulating methods
- Fluidised bed drier - spray drying using a binder solution
- Dry granulating - using pressure to form compacts
What are the benefits/ negatives of spray drying and dry granulating?
Spray drying - produces high quality granules - good homeogenity, flow and compactability. Time consusing
Dry granulation - no hydrolysis of drug
What is powder compression?
Pushing particles into close proximaty to each other by using confined compression
What are the 3 stages involved in powder compression to form a tablet?
- Die filling
- Tablet formation (compression of tablet from upper and lower die)
- Tablet ejection