Tablet Formulation & Preparation Flashcards
What are tablets?
Compressed solid preparations with a single dose of one/more active medicaments
Properties of tablets
1) Exact dosage of active principles
2) Confer maximum stability as possible
3) Possess suitable mechanical properties
4) Only contain inert additives/excipients
5) Aesthetically pleasing
6) Suitable for its intended purpose
Advantages of tablets
1) Convenient
2) Deliver accurate dose
3) Small & compact
4) Stable product
5) Easy to handle & pack
6) Possible for high production throughout
Disadvantages of tablets
1) Poor compressibility (b/c of poor binding/high elastic component)
2) Poor wetting
3) Slow dissolution
4) Tablet would be too big if require high dose
5) Moisture-sensitive
6) Bitter taste/bad odour???
Preparation & formulation of effervescent tablets
Formulation: Alkali metal carbonates/bicarbonates & organic acids such as tartaric acid, citric acid
Preparation:
1) Wet fusion
- Citric acid moistened, added to sodium carbonate, granulated
2) Heat fusion
- Powders blended dry, w citric monohydrate used; apply heat - water of crystallization liberated, aids granulation
Major excipients (MUST-HAVES)
1) Diluent/fillers
Purpose: For low dose drugs
Impt: Inert. Low $, Compactability, Good flow
Eg. lactose, starch (corn starch), cellulose (microcrystalline cellulose)
2) Binder/adhesives Purpose: Strength Eg. MCC - High strength, low friability, self-lubricant Modified celluloses (Methylcellulose) Synthetic polymers Gums (Sodium alginate)
3) Disintegrant
Purpose: Improve bioavailability (Ensures tablet will break up)
Eg. MCC, Starch, Sodium starch glycolate, Modified cellulose gum, Crospovidone
4) Lubricants
Purpose: Improve tabletability
Functional classification of excipients
1) Affecting compaction
- Diluent/fillers
- Binder/adhesives
- Lubricants/glidants/ anti-adherants
2) Affecting bioavailability/stability/marketing considerations
- Lubricants
- Disintegrants
- Colouring/ flavouring/ fragrance
Functional classification of excipients
1) Affecting compaction
- Diluent/fillers
- Binder/adhesives
- Lubricants/glidants/ anti-adherants
2) Affecting bioavailability/stability/marketing considerations
- Lubricants
- Disintegrants
- Colouring/ flavouring/ fragrance
Mechanisms of disintegrant action
1) Swelling (eg. Starches)
- Expansion when wetted
2) Wicking (eg. MCC)
- Interparticular bonds broken
3) Strain recovery (Eg. Crospovidone)
4) Interruption of particle-particle bond
5) Heat of interaction
- Enthalpy change cause dosage form to break up
Types of colorant
1) Dyes
2) Lakes (or lake pigments containing soluble dyes)
- Often applied as film nowadays b/c coating is expensive
Types of “Lubricants” & their MOA
1) Glidants
- Improve flow by ball-bearing effect (Reduce friction between particles)
Eg. Silicates, Mg stearate, Starch, Talc
2) Lubricants
- Reduce friction btwn granulation & die wall during compaction
Eg. Fluid type: Mineral oil/paraffin
Solid type: Mg/Ca stearate, stearic acid, waxes (H2O-insoluble)
Carbowax (PEG), Na benzoate/acetate, leucine (H2O-soluble)
3) Anti-adherants
- Prevent sticking/adhesion of tablets/granules/powders to the faces of the punches
Eg. Silicates & derivatives, Starch, Talc, Mg/Ca/Zn stearate
Machines for Tablet Press
1) Single punch tablet machine
2) Rotary/multi-station tablet machine
- Tablets formed by compression using punches of granules feed into dies
Compaction forces
Stress: Amount of force applied to produce deformation
–> Deformation: Change in relative parts of the body, expressed as a strain which is a change in length per unit length
What are the events in die during plastic recovery?
1) Die filling
2) Pre-compression (Particle rearrangement)
3) Main compression (Fragmentation, plastic deformation, elastic deformation)
4) Ejection (Elastic recovery)
What is tabletability?
Capacity of a powdered material to be made into a tablet of specified strength under the effect of compression pressure
