Tablets Flashcards
What is the physical description of molded tablets?
Soft, soluble and designed for rapid dissolution
How is molded tablets prepared?
They are prepared with molding rather than by compression
When is an inappropriate situation to use molded tablets?
For potent drugs due to difficulties with content uniformity
What does molded tablets not contain?
Disintegrates
Lubricants
Coatings
Explain the process of molding
Powder blend is moistened with hydroalcoholic solvent
Molded under pressure lower that compression
Solvent is removed by air during
Definition of chewable tablets
Intended to disintegrate in the mouth
What is the primarily intent for chewable tablets?
For children who prefer chewing a flavoured medication
Advantages of Chewable tablets
Pleasant taste
No bitter or unpleasant aftertaste
Convenience and pt acceptance
Rapid onset of bioactivity
What is the limitation of chewable tablets?
Number of drug that can be put into chewable tablets
What is the most common excipient in chewable tablets?
Mannitol
What makes mannitol better for chewable tablets
70% sweetness compared to sucrose
Cool taste and mouth fell
Non-hydroscopic
What is used for sugar free chewable tablets?
Xylitol
What is important counselling point for chewable tablets?
Do not swallow whole
Chew to break the tablet
Examples of Chewable tablets
antacids – Maalox, Tums
vitamins – Vitamin C, calcium
analgesics - aspirin – children’s chewable – often used for pets, acetaminophen
Anticonvulsant: carbamazepine
Angina pain medication: Isosorbide dinitrate*
antibiotics – amoxicillin
Define effervescent tablets
Large wafer like tablets which dissolve rapidly in water
What is the benefit of effervescent tablets?
Large surface area allows for faster rate of solution
What is released when effervescent tablets are breaking up?
Carbon dioxide generated from sodium bicarbonate and citric or tartaric acid
When is the chemical reaction initiated with effervescent tablets?
When it is placed in water
What is important considerations of effervescent tablets?
Binders, fillers and lubricants are water soluble
Moisture excluded during manufacturing
Packaged in moisture-proof containers to avoid degradation
Tablets individually wrapped in foil strip or wrapped and stacked in tubes
Flavoured & sweetened
Examples of effervescent tablets
Vitamin C
Calcium
Alka-seltzer
Important counselling for dispensing effervescent tablets?
Dissolve in water at room temperature
Once effervescence stops, wait >5 min and stir the solution for about 10 seconds then drink
Store away from humid conditions
Where is the tablet placed for sublingual tablets?
Under the tongue
Where is the tablet placed for buccal tablets?
In the side of the cheek
What is the purpose of sublingual tablets?
Designed to produce an immediate systemic effect by enabling drug to be directly absorbed through the oral mucosa
What is general physical description of sublingual tablets?
Are small, soft and flat
What is the purpose of buccal tablets?
They are designed to erode relatively slowly
What is RDT and ODT?
Rapidly dissolving tablets
Orally disintegrating tablets
What is the difference between sublingual and buccal tablets?
Require more than a minute to dissolve in the mouth
FDA definition of RDTs
A solid dosage form containing medicinal substances, which disintegrates rapidly, usually within a matter of seconds when placed upon the tongue
What is the benefit of ODT?
Enchanted clinical effects through pre-gastric absorption front eh mouth, pharynx and esophagus
Increase the bioavailability
What is done in packaging to protect ODT from moisture?
Packaged in blister packs
Patient information for ODT
Do not try to administer tablets with wet hands
Store tablets in a dry place
Certain products may cause a burning or prickling sensation on the tongue
Challenges of ODT and (sublingual)
Drug loading
Taste masking and palatability
Friability
Extra cost of packaging
What is the challenge of friability?
Balance difficult to maintain a between friability and speed of dissolution
What is benefit of lozenges
Promote saliva flow (which is soothing)
May be used for systemic effect (if absorbed by buccal lining)
Examples of lozenges
Fentanyl (lollipop)
Nicotine
Sore throat
Flurbiprofen
Zinc
What patients who lozenges are useful for?
Difficult swallowing
Paediatric pt
Geriatric pt
Pt with GI blockage
How are lozenges prepared?
Prepared by molding or compression
What is another name for molded lozenges?
Pastilles
What is another name for harder lozenges?
Troches
Compressed lozenges are different
They are harder
So they will slowly dissolve or disintegrate
What is the basic properties of a good lozenge?
Slow uniform dissolution or erosion over 5-10 minutes period
Smooth surface texture
Pleasant flavour masking drug taste
What are some therapeutic use for lozenges?
local anaesthetics (benzocaine)
antiseptics/antimicrobial
antitussives (cough drops)
decongestants
Antihistamines
anti-nausea
analgesics
What are the ingredient in a compounded lozenges?
Sugars to form a hard lozenge
PEG to form a soft lozenge
Gelatin to form a chewable lozenge
Composition of hard lozenges
Might be considered solid syrups
What is the percentage of sucrose and corn syrup for hard lozenges?
55-65% sucrose
35-45% corn syrup
What is a critical step for hard lozenges?
To follow all formation instructions and pay particular attention to temps
Is hard lozenges high or low moisture content?
Low (0.5-1.5%)
So the water is evaporated off by boiling the sugar mixture during the compounding process
What is the benefit of soft lozenges?
Can be hand rolled
Then cut into pieces which contain the correct amount of active ingredient
More convenient dispensing method
What is the composition of soft lozenges
PEG 1000 or 1450
Chocolate
Sugar acacia base
Silica gel
What is acacia
Used to add texture and smoothness
What is silica gel
Used as a suspending agent to keep materials from settling to the bottom of the mold cavity during the cooling process
What should be changed in the compounding steps if using PEGs?
The mixture will need to be overfilled as PEG contract once cooler
What is the composition of chewable lozenges?
Glycerinated gelatin suppository formula which consists of glycerin, gelatin and water
What is capping?
The partial or complete separation of the top or bottom crowns of a tablet from the main body of the tablets
What is lamination?
The separation of a tablet into 2 or more distinct layers (transverse cracking and separation of tablets)
List the causes of lamination/capping
Air entrapment in light and fluffy powders
Excessive “fines”
Too little moisture in granulation
Weak granules or too weak a binder
Improver adjustment of machinery
What is picking?
The surface material from a tablet that is sticking and being removed from the tablet surface by a punch
What is sticking?
Tablet material adhering to the die wall
List causes of picking/sticking
Inadequate lubrication
Insufficiently dried wet granulation
Poor finish on punch surfaces
What is whispering?
Fine edge attached but not broken off tablet
End up with high friability values since whiskers are removed in friability testing
List causes of whiskering
Especially deep concave punches
Punches worn and in poor condition
What is chipping/splitting?
Tablet either chipped or split in half
List causes of chipping or splitting
Poor finish or worn punches and dies
What is friability?
The ability of the compressed tablet to withstand abrasion or crumbling in packaging, handling and shipping
List the causes of friability
Inadeqaute bonding of tablet mix
Too much or too little pressure
Worn punches or dies
List causes of poor disintegration
Tablets hardness too high
Low amount of disintegrant
Too much binder
Over lubrication causing “waterproofing”
What is mottling?
An unequal or uneven distribution of colour on or in a tablet
List the causes of mottling
Uneven distribution of powdered lakes
Soluble dye migration during drying
What is low hardness?
Can lead to rapid release of drug from form or tablet will be too fragile for shipping and handling
List causes of low hardness
Compression pressure too low
Binder can affect the hardness of a tablet
What are some traits of tablets?
Solid dosage forms
Prepared by compression or molding
Contain on or more medicinal substances
What are some parts in a tablets?
Drug
Diluents
Disintegrants
Colourants
Coating
Binders
What is the prep stages of compressed tablets?
Powders
Compression
Tablets
What is the problem with compressed tablets?
Simple powders may have poor flow and compression characteristics
They require tremendous pressure and the resulting tablet may not have desired characteristics
What is the solution to the main problem of compressed tablets?
Materials to be compressed usually require some modification such as formation of granules (helps with cohesive and flow)
Define granulation
The process of particle size enlargement of powdered ingredients
What is the commonly used processed methods?
Wet granulation
Dry granulation
What is the advances in the wet granulation process?
Fluid bed granulator
Microwave vacuum processing
Explain fluid bed granulator
Whole process in one machine through fluidized air movement
Define microwave vacuum processing
Use of microwaves reduces the drying time by one fourth
What is another name for diluents?
Fillers
Purpose of diluents
Acts as a vehicle/carrier for the drug
Increase the bulk of the tablets
Help improve or maintain content uniformity
Diluents comprise from as little as 5% to as much as 80% of total weight
Examples of diluents
Lactose
Dextrose
Starch
Mannitol
Microcrystalline cellulose (MCC)
What is a binder?
Often considered the most critical ingredient
They impact cohesiveness to powders therefore providing the necessary bonding to form granules which are then compacted into tablets
Explain how the amount of binder is critical
Sufficient binder is necessary to maintain an intact tablet during transit , dispensing and handling
Concentration range varies from 1 to 20%
What percent is diluents?
5-80%
What percentage is binders?
1-20%
Examples of binders
Starch
Gelatin
Glucose
Polyvinylpyrrolidone (PVP)
Can tablet excipients work as more than one function?
Yes
What does dextrose, sucrose and lactose do?
They exhibit binding properties
What two functions can starch and MCC have?
Binding and disintegrate properties
What functions can lactose and sucrose both have?
Impact hardness
What does starch, kaolin and dextrose add?
Softness
What does mannitol, lactose and sorbitol add?
A cooling effect
What is the properties that lubricants add?
Gliding effect
Anti adhesive effect
Acts as lubricant
Explain gliding effects
Provide by coating and lubricating particle surfaces
This helps improve flow properties of tablet granulation
Explain anti-adhesive effects
Prevents adhesion of materials to punches and dies during tablet compression
Explain why lubricant is needed
It is need between walls of die cavity and tablet
Helps to facilitating tablet ejection
List examples of lubricants
Magnesium stearate
Stearic acid
Talcum
What percentage is lubricants?
<1 %
What is the purpose of disintegrants
Facilitates the break-up of a tablet after administration
Causes the tablet to rupture or break apart when it comes in contact with the aq fluid of the GI tract
Facilitates disintegration, dispersion and dissolution of tablets
Mechanism of disintegrants
Involves porosity, capillary action and swelling
It is believed to draw gastric fluids into the tablet, causing porosity in the tablet or swelling and finally break up due to hydrostatic pressure
Examples of disintegrants
Starch
Microcrystalline cellulose
Sodium bicarbonate & citric/tartaric acid
Function of colouring agents
To enhance esthetician quality
To provide distinctiveness to the product/ to aid in product identification
Colourants must be approved by regulatory bodies
Function of flavouring agents
to make it taste better for better compliance
What are required for chewable and effervescent tablets?
sweeteners and flavoring agents
What are some examples of flavoring agents?
peppermint
vanilla
cherry
What is the purpose of moleded tablets?
makes soft, easily disintegrating tablets
designed for rapid dissolution
Why should combining with calcium salts with tetracycline?
it interferes with absorption of tetracycline from the gut
What the preparation of a compressed tablets?
prepared by compression using tablet presses the basic mechanical unit is a punch and die set
What does the basic mechanical unit for tablet compression consists of?
lower punch
upper punch
die
Explain the feeder
transfer of granules into position in the die cavity
Explain the metering
leveling of the granule/powder contents in the die, removal of extra granules
the position of the lower punch in the die is responsible for the volume of the cavity which is adjusted depending on the weight of the granules
Explain of compression
top and bottom punches come together by pressure within the die to form the tablet
as this stage approaches, the top and bottom punches move between two large wheels called compression rolls
the distance between top and the bottom punches define the thickness and hardness of the tablet
Explain the ejection
the upper punch retracts from the die cavity, the lower punch rises in the die and pushes out the tablet
then by the scrapper tablets are collected in the container
What is the purpose of tablet coating?
smooth surface
product identification
mask drug taste
improve drug stability in the tablet
What are some functions of coating?
enteric coating
controlled/sustained release
Types of Tablet coatings
sugar coating
film coating
functional coating
Potential problems with sugar coating
many steps of this process involve tumbling -tablets must be hard enough to withstand it
must mix uniformly or coating goes on unevenly resulting in tablets of different sizes and weights
What is the common coating?
film coating
What is the film coating process?
tablets move through a zone where the coating material is applied
via a coating pan, spray in a fluidized stream, or press coating
Factors of Mixing of Tablet mass
pan shape, rotational speed and loading affect the mixing of tablets and coating
What is essential to deposit the same quantity of film?
uniform mixing
What can cause unacceptable color uniformity?
poor tablet movement in coating pan
What is a compression coating?
compaction of a dry coat around a tablet core, produced on the same tableting machine
What is used to create a layered tablet?
compression coding
Is organic or aqueous film coating preferred? Why?
Aqueous is preferred because organic is expensive and sometimes not environmentally friendly
What are some challenges when it comes to aqueous film coating?
slow evaporation of water
orange peel effect
bridging
tablet erosion
What is the orange peel effect?
roughness of coating on tablet surface due to failure of spray droplets to coalesce
What is bridging?
covering of score line or monogram on the tablet due to longer drying times
What is tablet erosion?
disfiguration of the core tablet when subjected to the coating solution for too long
Explain enteric coating
allows for disintegration in the intestine rateher than the stomach
could be a type of film coating
Explain CAP
cellulose acetate phthalate is the most common material used in enteric coating
Explain Functional Coatings
allow for timed release can have particles coated with varying thickness of coating so drug is released gradually from the dosage unit
What are some physical features of tablets?
general appearance
size
shape
organoleptic properties
What are some factors of general appearance of tablets?
texture
scoring
engraving
What are some factors of size of tablets?
diameter & thickness
What are some factors of shape of tablets?
oval
oblong
triangular
flat
What are some factors of organoleptic properties?
color
odour
taste
What are some other important physical specifications of tablets?
tablet weight
thickness
hardness
disintegration
content uniformity
drug dissolution
What are some tests for tablets?
tablet hardness
friability test
drug content uniformity
drug release
Explain tablet hardness test
a function of die fill and compression force
tablets should be sufficiently hard. toresists breaking or chipping during packaging shipping and normal handling yet soft enough to disintegrate or dissolve properly after administration
Define tablet hardness
as the force required to break a tablet in a diametric compression test
Explain friability test
tablets are allowed to roll and fall within a rotating tumbling apparatus
tablets are weighed before and after a specified number of rotation and the loss in weight is determined
Define friability test
ability of tablet to withstand abrasion in packaging, shipping and handling
in other words its tendency to crumble
What are the two drug content uniformity test?
weight variation
content uniformity
Explain the weight variation test
Relies on tablet weight to assess the amount of drug in each unit
The greater the amount of drug the more accurate the method is
Explain the content uniformity
Assesses uniformity of content by assaying each dosage unit
Needs to be around 15% range within a relative standard deviation of <6 %
The importance of dissolution test
Since drug absorption and bioavailability are dependent upon the drug being dissolved state
The purpose of the dissolution testing
Shows that
The release of the drug from a dosage form is around 100%
The rate of release is uniform from batch to batch
The rate of release is the same as the release rate from those batches proven bioavailability and clinically effective
When is the dissolution testing useful?
In the early stages of drug development & formulation to optimize the dosage form characteristics
What two drug release test need to be performed?
Disintegration and dissolution
What is the measure of a pass or fail of disintegration?
Six tablets are agitated in a given medium (water) at 37 C
The tablets must disintegrate within a specified time period
What is disintegration tests used for?
As a mean to ensure that there is batch to batch consistency with respect to disintegration
