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