tablet PR_9 Flashcards
what are tablets
compressed solid preparation with a single dose of one or more active medicaments
shape of tablets
usually circular in shape with flat beveled or biconvex faces
properties of oral compressed tablets
- intended for swallowing
- usually disintegrate in stomach
- some, with specialised function (eg. enteric-coated, modified release, effervescent, sublingual, lozenges)
effervescent tablets
- rapid disintegration in water, achieved by liberation of carbon dioxide
- formulation include: alklai metal carbonates or bicarbs and organic acids (tartaric acid, citric acid)
- prepared by wet or heat fusion technique
describe wet and heat fusion techniques
heat fusion: powders blend dry, with citric monohydrate used; apply heat, water of crystalisation liberated, aids granulation
wet fusion: citric acid moistened, add to sodium carbonate, granulate (cirtric acid fuse powders)
properties of tablets
- have exact dosage of active principle
- confer maximum mechanical properties
- contain only inert additives/excipients
- aesthetically pleasing
- suitable for its intended purpose
advantage of tablets
- convenient means of administering
- delivery an accurate dose
- small and compact
- stable product
- easy to handle and pack
- high production throughput possible
disadvantage of tablets
- poor compressibility
- poor wetting
- slow dissolution
- high dose
- bitter taste/ bad odour
- sensitive to moisture
requirement of tablets
- low dose drug (filler)
- strength (binder)
- bioavailability (disintegrant, wetting agent)
- tabletability (lubricant)
- identity (colorant)
Major types of excipients
- diluent/filler
- binder/ adhesive
- disintegrant
- lubricant
minor types of excipients
- absorbent
- stabiliser
- wetting agent
- colorant
excipients that affect compaction properties
- diluents/ fillers
- binders/ adhersives
- lubricants, glidants, anti-adherents
excipients that affect bioavailability, stability and marketing considerations
- lubricants
- disintergrants
- colors, flavours, sweeteners
diluents/fillers
- sugars: lactose (hydrate anhydrous), sucrose based
- starches: corn starch, pregelatinised
- celluloses: microcrystalline cellulose (large variety)
- inorganic salts: Dicalcium phsophate
mainly: inert, inexpensive, good flow, good compactability
binders/adhesives
- cellulose: microcrystalline cellulose (high strength, low friability, self lubricant, dry binder)
- modified cellulose: methylcellulose, hydroxypropylmethylcellulose, hydroxypropylcellulose, sodium carboxymethylcellulose
- synthetic polymers: polyvinylpyrrolidone,PVP/vinyl acetate
- gums: sodium alginate, acacia, gelatin
types of disintegrant
- starch
- microcystalline cellulose
- sodium starch glycolate
- modified cellulose gum
- cross linked polyvinypyrrolidone
mechanism of disintegrant action
- swelling (starch)
- wicking - cap action (microcrystalline cellulose)
- strain recovery (crospovidone)
- interruption of particle-particle bonds (microcrystalline cellulose)
- heat of interaction
colorant
- added to provide color to tablet
- often added wet with granulation liquid
- may be added dry (need more dye)
types of colorant
- dyes (soluble or insoluble pigment types)
2. lakes (contain soluble dye deposited onto carrier particles, usually metallic salts
lubricants
- glidants: improve flow properties of granules/ powders by reducing friction between particles (ball bearing effect)
- lubricants: reduce friction between granulation and die-wall during compaction
examples of glidants
- silicates
- fused silica
- starch
- talc
- mg stearate, carbonate, oxide
- Ca/ Zn stearate
types of lubricants
- hydrodynamic (fluid type): mineral oil/ paraffin
- boundary (solid type):
- water insoluble: Mg/Ca stearate, stearic acid, hydrogenated veg oil (steotex), waxes
- water soluble: carbowax (PEG), Na benzoate/acetate/lauryl sulphate, leucine
Anti-adherents
- silicates and derivatives
- starch
- talc
- Mg, Ca, Zn stearates
- leucine
- sodium lauryl sulphate
tableting machines
- single punch (single station) tablet machine
2. rotary (multiple station) tablet machine
stress of compaction forces
the applied force to produce a deformation
deformation
change in the relative positions of different parts of the body, expressed as strain which is a change in length per unit length or volume per unit volume
compaction cycle (compression over time)
loading 1. repacking 2. elastic deformation 3. plastic deformation 4. brittle fracture 5. visco-elastic deformation unloading 6. elastic recovery 7. plastic recovery ejection 8 visco-elastic recovery
tabletability
capacity of powdered material to be made into a tablet of specified strength under the effect of compression pressure
compressibility
ability of material to undergo volume reduction when subjected to an applied pressure
compactibility
Ability of material to produce tablets with sufficient strength under the effect of densification
mechanical strength of tablets depends on
- particle size, distribution, shape
- granule porosity
- moisture content
- fragmentation and visco elastic deformation
- applied load (copaction force)
- time of loading (strain rate sensitivity)
- time of unloading (strain rate sensitivity)
- elastic stress release uppon ejection
material requirement for tabletting
- ideal brittle- plastic balance for good compressibility
- adequate granule porosity for compressibility
- sufficient moisture content for correct compressibility
- good powder flow for ideal tabletability
- correct level of lubrication for good compatibility
causes of capping
- air entrapment
- mechanism of volume reduction
- compression speed
- viscoelastic recovery
- stress density distribution
- internal shear stress
remedies for capping
- lower compression forces
- reduce compression speed
- decrease ejection path in the die
- tool design change
- extend dwell time
dfference in plastic and brittle material
plastic: under compressive forces will deform irreversibly
brittle: under compressie forces will deform by breaking down into small fragments
why continuous manufacturing
- cost efficient
- efficient and robust process development
- improved product quality
- flexible
- reduced environmental impact
how does CM work?
- powder feed
- blending granulation
- drying
- milling external phase lubricant
- compression
- coating
