Lab 5: Evaluation Of Tablets Flashcards
How is the general appearance of a tablet evaluated?
By visual observation, taking into account
the tablets
Shape (e.g. Spherical, oblong, almond shaped, heart shaped)
colour (e.g. White, off white)
surface (e.g. Smooth, rough, shiny)
Odour (e.g. Vinegar, mint)
Why do we need to do quality control evaluations on tablets?
There are various properties of tablets which can undergo change due to environmental or stress conditions. This will affect their bioavailability
What is the general appearance of panadol tablets ?
Spherical, white tablets with. Smooth surface.
Odourless
How is the uniformity of size test evaluated?
By measuring the diameter and thickness of 20 individual tablets single an electronic Vernier Caliper.
The individual and average values are recorded.
Why is hardness of tablets evaluated?
This test helps to determine the resistance to crushing of tablets as during their shipping and handling they will be subjected to physical stress.
How is the hardness test evaluated?
By measuring the force required to crush the tablet (vertically) i.e. Applying the force through the diameter of the tablet.
This is done using a Monsanto hardness tester.
10 tablets are evaluated and their individual and average values are recorded.
Tablets must be a minimum of 4kg/cm^2
Why is the friability test conducted?
This measures the ability of the tablet to be easily crumbled or reduced to a powder.
This is designed to evaluate the ability of the tablet to withstand abrasion in packaging, handling and shipping
How is the friability test conducted?
If the tablet unit mass is 650mg, 10 tablets are evaluated.
The sample of tablets are weighed, and then placed in the friability unit which rotates 100 times at 25rpm. The loose dust is removed and the tablets are re weighed.
There should not be more than 1% of mass loss.
Cracked or broken tablets = fail.
If difficult to assess samples, take the mean of 3 measurements
How is the uniformity of weight evaluated?
20 tablets are weighed individually to determine the average mass using an electronic balance.
Deviations from the average is calculated in %s
The panadol tablets were >250mg, so BP specifies no more than 2 should deviate by more than 5%, and none should deviate by more than 10%
When is uniformity of content tested?
Then the average mass is less than or equal to 40mg
Why is the disintegration test conducted?
To determine whether tablets or capsules disintegrate within the prescribed time when placed in a liquid medium under specific environmental conditions
What is classified as complete disintegration?
When the residue of the unit remaining on the screen of the test apparatus or adhering to the lower part of the disc is a soft mass having no firm core
How is the disintegration test conducted?
6 tablets are dropped at the same time in the disintegration apparatus (1 tablet in each tube)
The discs are placed on top of each tablet in each tube.
The apparatus is set to operate at 37°C +/- 2°C
If non enteric coated, all tablets should disintegrate complete.
If more than 1 fails to do so, the test should be related on 12 additional tablets and 16/18 of the tablets should have disintegrated.
Why is evaluating the general appearance of size, shape and thickness of tablets important?
To facilitate packaging and to decide which tablet compressing machine to use
Why is determining the organoleptic properties (including colour and odor), of a tablet important?
This is a vital means of identification of many pharmaceutical tablets and is also usually important for consumer acceptance.
What are the acceptable ranges of colour in a batch of tablets?
Colour should be uniform within a single tablet, from tablet to tablet and from batch to batch
What are the acceptable variances in odour of tablets?
Odour provides an indication of the quality of tablets as presence of an odour could suggest a stability problem e.g. The characteristic odor of acetic acid in degrading aspirin tablets.
The presence of an odour may also be characteristic of the drug e.g. Vitamins, added ingredients e.g. Flavouring agent, or the dosage form e.g. Film coated tablets
What are the quality control tests?
Weight uniformity and content uniformity
Dissolution test
Weight variation, thickness and diameter
Hardness and friability
Why is weight uniformity and content uniformity tested?
Tablets should include the correct dose of drug
Why is dissolution tested?
Drug should be released from tablet in a controlled and reproducible way
Why is weight variation, thickness and diameter tested?
Appearance of tablet should be elegant.
Its weight, size and appearance should be consistent
Why is hardness and friability tested?
Tablet must show sufficient mechanical strength to withstand fracture and erosion during manufacture and handling.
These factors must be controlled during production and verified after production i.e. In process control
What is tablet weight affected by?
Factors such as
Head pressure of compression machine
Machine speed
Flow properties of the powder.
What is hardness?
The load required to crush the tablet when placed on its edge
Why is hardness measured?
To determine the pressure adjustments on the tableting machine
Hardness affects disintegration, if tablet is too hard it may not disintegrate in the required period of time.
If tablet is too soft it will not withstand handling during subsequent processes such as coating and packaging
What happens if the tablet hardness is too high?
First we check its disintegration before rejecting the batch.
If the disintegration is within its limits we can ac pet the batch
What factors affect the hardness of tablets?
Compression of tablet
Compressive force
Amount of binder (more binder increases the hardness)
Method of granulation in preparing tablet (wet method gives more hardness)
Limit: min 4kg/cm^2 as the average of 10 readings
What is friability?
The tendency of tablets to powder, Chip or fragment.
This can affect the elegance, appearance, consumer acceptance.
It also adds to the tablets weight variation or content uniformity problems
What is friability related to?
The hardness of the tablet,
Its weight variation
And the content uniformity
What is the instrument used to measure friability?
A friabilator is used to evaluate the ability of the tablet to withstand abrasion in packaging, handling and shipping.
In this unit the tablet is subjected to a tumbling motion
What is another application of the friability test?
To detect capping or laminate when tablets are subjected to stress inside the rotating cylinder present in the friability tester
What is capping?
The partial or complete separation of the top or bottom crown from the main body of the tablet
What is lamination?
The separation of the tablet into two or more distinct layers
What is disintegration?
The time required for the tablet to break into particles
The disintegration test is a measure of the time required under a given set of conditions for a group of tablets to disintegrate into particles
How is the disintegration test different in the evaluation of un coated tablets?
The apparatus is operated for 15 minutes,
If tablets fail to comply due to adhering to the discs, the results are invalid and the test must be repeated on a further 6 tablets without the discs
How is the disintegration test different for coated tablets?
The apparatus is operated for 60min or 30min for film coated tablets.
If any of the tablets have not disintegrated, the test is repeated on 6 more tablets and the water is replaced with 0.1M HCl
How is the disintegration test different when evaluating effervescent tablets?
ONE tablet is placed in a beaker which contains 200mL of water at 15-25°C
When the evolution of gas around the tablet or its fragment ceases, the tablet has disintegration
This is then repeated on 5 other tablets.
Tablets are said to comply if each of the 6 tablets used disintegrate in the manner prescribed in 5mkns
