Solid dosage forms Flashcards
What are some of the disadvantages of tablets?
manufacture requires a series of unit processes - product loss at each stage
drug absorption is dependent on gastric emptying rate
compression difficulties due to powder physical properties
What is the definition of excipient?
An inert substance that is used as a diluent or vehicle for preparing a drug product
For high dose tablets, the active ingredient is < 5% of the tablet weight. True or false?
False >50% of tablet weight
For low dose tablets, what % of tablet weight dose the active ingredient make?
< 5%
The total tablet weight should be less than ___mg to be viable to swallow
800mg
High dose tablets require a filler. True or false?
False - low dose <5mg tablets do
The filler used in tablets should be hygroscopic. True or false?
False - non-hygroscopic as you don’t want it to absorb water as they make bulk of tablet
Why is a filler needed in a low dose tablet?
For ease of manufacture and handling
What is the need for a disintegrant in a tablet?
To ensure the tablet breaks up into smaller fragments
What is the role of a binder in a tablet?
Added to ensure that the tablet can be formed with the required mechanical strength
What is the role of a glidant in a tablet?
To improve flowability of the powder - either for direct compaction or for granulation
Name a glidant
talc
Name a binder
PVP
Name a filler
Sucrose
Name a disintegrant
Starch
What is the role of a lubricant in a tablet?
To ensure that tablet formation and ejection can occur with low friction between the tablet and the die
Name a lubricant
Magnesium stearate
Why would you want to minimise the amount of lubricant in a tablet, although it helps with tablet formation?
Because they are usually lipophilic and so will hinder the dissolution and disintegration of the tablet if too much is used
What is the role of an antiadherent in tablet?
To reduce the adhesion between the powder and the punches which could otherwise lead to uneven tablet surface
What is tensile strength used to measure?
adhesive/cohesive properties
What is meant by tensile strength?
How easy it is to introduce a breakage in the tablet
What does a high angle of repose indicate?
High cohesive forces
When the angle of inclination is greater than the frictional force, does the powder slide or stop sliding?
Slide
How can powder flow be improved?
Increase the particle size of powder e.g. by granulation
Alter surface forces - controlled temp, humidity etc.
Formulation additives e.g. glidants, lubricants
Change process conditions - vibration assisted hoppers, force feeders
What is granulation?
Primary powder particles are made to adhere to form larger multi-particle entities called granules
Why use granulation?
Granules flow better than powder
Prevent segregation of ingredients
Improve compaction
Ease of transport as they are less dense than powder and so occupy less vol/unit weight
What is the mechanism of granulation? (3 steps)
Nucleation
Transition (nuclei growth)
Granule growth
Wet granulation is suitable for temperature and moisture sensitive material. True or false?
False - dry granulation is
What are some advantages of dry granulation?
Economical - less energy costs
Low equipment costs
Easy to scale up
Bulk density affects die filling. True or false?
True
Uniformity of content test is recommended for all pharmaceutical preparations. True or false?
False - compulsory
How many tablets should be tested for uniformity of content?
More than 5 - to be representative
What are the accepted % limit for API in uniformity of content test?
90-110%
There is a direct correlation between uniformity of content and tablet weight. True or false?
True
In tablet weight testing, no more than two tablets should have a mass difference of more than 20%. True or false?
False - 10%
What happens to a tablet that is ingested but doesn’t disintegrate in the body?
It gets excreted
How many tablets need to fail the disintegration test for it to be repeated on a second full batch?
2 tablets
What is the definition of dissolution?
The transfer of molecules or ions from the solid state into solution
What are the two methods of conducting dissolution tests?
Stirred vessel method
Continuous flow method
Dissolution is independent of temperature. True or false?
False - dependent on temperature
If a reaction is exothermic, will dissolution be favoured by an increase in temperature?
No
What are the two possible apparatus for dissolution in the stirred vessel method?
Basket
Paddle
Which dissolution method is a better mimic of GIT conditions?
Continuous flow
The mechanical strength of a tablet it associated with resistance of the solid specimen to what two thing?
Fracturing and attrition
What are friability tests used to mimic?
Forces that are present in production, storage and administration
In the friability test you are looking for a less than 5% weight loss in the tablet. True or false?
False - less than 1%
In a friability test, how many tablets are tested?
20 tablets in revolving cycle
When testing the tablets resistance to crushing, if the tablet splits in two, does it pass the test?
Yes
What are gastro-retentive tablets designed for?
To be retained in the upper GIT
Mucoadhesive tablets are designed to stick for a long period of time. True or false?
True
What are the 3 types of coating?
Film
Sugar
Compression
What is titanium dioxide used as in coating?
A colourant
Are tablets more evenly coated if a horizontal spray is used or a tilted spray is used?
Tilted
What are some problems that are associated with coating?
Erosion, peeling and breakage
Poor mechanical strength
Uneven coat
Tablet peeling
Sugar coating involves successive applications of ______ solution
sucrose
What are the characteristics of tablets that are coated with a sugar coating?
Immediate release of drug - as sugar is very soluble in water
Masked taste of tablet
Main reason of using a sugar coating is for masking taste rather than functionality. True or false?
True - would still need a film coat e.g. enteric if you want functionality
A sugar coat doesn’t add much weight to the total tablet weight. True or false?
False - adds a lot of weight 30-50%
Sugar coating a tablet is a quick process. True or false?
False - takes over 8 hours
What are the 6 steps involved in sugar coating process?
Sealing Subcoating Smoothing Colouring Polishing Printing
Compression coating allows for 2 drugs to be present in one tablet. True or false?
True - one drug in the coating and one in the core
Soft gelatin capsules cannot be filled with liquid. True or false?
False - can be filled with liquid - helps to increase solubility or permeability of drug across cell membrane
Soft gel capsules are not suitable for potent drugs. True or false?
False
Why is there no risk of leakage in a soft gel capsule?
Because it is one piece that is sealed
Why is it harder to have a liquid in a hard capsule?
Because there is risk of leakage - the capsule is made of two pieces
Hard capsules are all one size. True or false?
False - they can be different sizes to accommodate for different volumes within the capsule
Hard capsules are filled with liquid. True or false?
False - powder, or more normally pellets
The hard capsule shell doesn’t give any controlled release properties. True or false?
True - if you want controlled release, this has to be done at the granulation stage of the process
Hydrolysis only occurs in the presence of water. True or false?
False - water, acid or base
Most ibuprofen is supplied as a racemic mixture. Unusually, this drug is converted to the R-form in the body. True or false?
False - converted to the S form
What does a maillard reaction occur between?
Lactose and an amide containing drug, resulting in a glycosylamine.
How can a maillard reaction be prevented?
By using an alternative diluent to lactose such as mannitol
Replacing an aqueous solvent with a non-aqueous solvent will maximise the stability of the drug. Why?
Because it will be less prone to hydrolysis
Magnesium stearate only acts as a lubricant. True or false?
False - lubricant, glidant, anit-adherent
