L52 - Processing Of Tablets Flashcards
What’s a drug?
Chemical compound
What’s an excipient?
All the other components of a formulation other than the active drug
What is a medicine?
A drug in a form suitable for administration to the public
What is a tablet?
A compressed powder consisting of drug and inert excipients
What is a capsule?
Drug and excipients contained in a gelatin shell
What is a caplet?
A compressed powder in the shape of a capsule
What are the different types of tablet? (8)
- uncoated
- sugar, film, press coated
- controlled release
- effervescent
- soluble
- chewable
- sublingual
- lozenges
What are the advantages of tablets? (7)
- accurate, min variability
- convenience
- physicochemical stability
- tailored rate of release
- mass production
- simple and cost effective
- patient acceptability
What are disadvantages of tablets? (5)
- swallowing
- difficulty preparing certain formulations
- poorly wetting, low sol drugs
- bitter taste, bad odour
- O2, moisture sensitive = req coating
What are essential properties of tablets? (7)
- accurate, uniform dose
- uniform weight, appearance, size/shape
- recognisable
- withstand stress of processing
- rapidly breakdown
- appropriate and reproducible dissol rate
- moisture, temp stability
What are the 3 vital properties requires for a particulate system?
- must be sufficiently free flowing
- cohere to form a compact when forced
- adhesion of tablet must be avoided
Why are excipients required?
Relatively few API possess the essential properties
What are the steps in making a tablet? (8)
- weighing
- dry mixing
- granulation
- tableting
- QA check
- dissolution
- coating
- QC check
What are the main steps that tablet machines do? (4)
- powder filled to specific depth in die
- formulation compressed between two punches
- compression force ended by removal of upper punch
- lower punch moves upwards to eject tablet
What are the 2 types of presses?
- single (eccentric) punch presses
- rotary presses
What are the 3 stages of compression of powder bed?
- rearrangement of powder bed upon application of stress
- deformation of powders due to applied stress
- bonding of compressed powders
What happens in stage 1 - rearrangement? (5)
- at low stress levels
- inital stress - densification of powder
- particles rearrange - minimise free space
- extent dictated by particle size distrib and frictional forces
- inc pressure - no relative particle movement = deformation
What happens in stage 2 - deformation? (4)
- inc compression force = deformation
- red compact volume = deformation
- permanent changes in shape of material occur
- physicochemical and mech properties affect nature and type of deformation
What are the different types of deformation mechanisms? (3)
- elastic
- plastic
- brittle fragmentation
What undergoes plastic deformation? (4)
- microcrystalline cellulose
- stearic acid
- starch
- sodium chloride
What undergoes fragmentation? (4)
- sucrose
- dibasic calcium phosphate
- lactose
- calcium carbonate
What happens in stage 3 - bonding? (3)
- after sufficient stress and deformation
- inter particle bonding occurs
- = tablet
What is essential in dry mixing? (3)
- must be well blended for uniformity
- all ingredients are free of lumps and agglomerates
- sieve raw materials = reliable and reproducible
What happens in the direct compression procedure? (3)
- desired particle size achieved
- compressible vehicle dry blended with other excipients
- blend is compressed
