Tablets are manufactured by the combination of API ( active pharmaceutical ingredients) and excipients.Both API and excipients have a critical role in the manufacturing of tablets despite having the fact that excipients have no pharmacological effect.
Understanding Excipients
The inert substances used in table manufacturing are known as excipients, or the substances which have no pharmacological effect, are known as excipients.
From the definition of excipients it is clear that these have no pharmacological effect so one may think about why these are used in formulation of tablets?
The answer lies in the statement that without excipients the API can’t perform its function, but how?
- Excipients act as a carrier for active pharmaceutical ingredients and are required to give specific characteristics to the dosage form & without these characteristics, the API can’t perform its function.
- In simple words, excipients are required to enhance bulk volume for easy handling, enhance solubility, stability and dissolution profile.
- Excipients are also added in the tablet formulation to mask the taste or colour and to prevent various manufacturing defects like sticking, picking & weight variation.
List Of Excipients For Tablet Manufacturing
Here is the list of most commonly used excipients for tablet manufacturing
- Diluents
- Binders
- Disintegrants
- Lubricants
- Glidants
- Flavourants
- Sweeteners
- Colourants
Diluent
Diluents are the excipients which are used in the tablet manufacturing to increase the final bulk volume.
Suppose we have 10 mg of API for a tablet formulation and after adding other excipients, its weight reaches 30 mg but it is too low to compress.
We will increase the bulk volume to make the final volume compressible, meaning we will add 70 mg of the diluent, and will easily compress the tablet at 100 mg.
Diluents are also known as fillers or bulking agents, so don’t be confused when someone asks you regarding fillers or bulking agents.
All the substances in a formulation other than active pharmaceutical ingredients are known as excipients.
Example of diluents
For tablet manufacturing, the most commonly used diluents are given below
- Lactose
- Dextrose
- Mannitol
- Starch
- Xylitol
- Magnesium Oxide
- Pregelatinized Starch
- Dibasic calcium phosphate
- Tribasic calcium phosphate
- Microcrystalline cellulose
Also Read
Classification of tablet diluent
Binders
Binders are the substances which are used in tablet formulation to give cohesiveness to powder particles.
Binders are the excipients which bind the powder particles to form granules and prevent various tablet compression defects like capping and lamination.
Apart from the fact that binders are very important for tablet manufacturing, their quantity may also have a negative impact on the properties of compressed tablets.
If binders are used in a higher quantity, they will result in prolonged disintegration time and poor dissolution profile, so always use binders in an optimum concentration to get their desired results.
Examples Of Binders
- Starch
- Gelatin
- Gum Cassia
- Tragacanth
- Gelatin
- HPC
- HPMC
- Kollidon
Detailed Article
Read details of tablet binders
Disintegrants
- Disintegrants are the excipients which are used in tablet formulation to break down the tablet into smaller particles to release the drug.
- We are familiar that tablets are compressed from powders or granules by applying pressure, so this tablet must release the drug after its intake.
- Disintegrants play their role when they come in contact with fluid by breaking the tablets into granules and granules into powders so the drug is available for pharmacological activity.
Imagine a formulation without disintegrants where we manufacture granules using binder and other excipients & these granules are compressed into tablets.
When these tablets are subjected to a disintegration test, tablets fail to disintegrate because, to break down tablets into smaller particles, we must have disintegrants in our formulation.
There are two types of disintegrants
- Conventional disintegrants
- Super disintegrants
Conventional disintegrants are those excipients which are required in large quantities to perform their disintegrating properties.
Example
- Starch
Super disintegrants are those excipients which perform their activity in a small quantity and are more effective.
Example
- Sodium starch glycolate
- Croscarmellose sodium
Also Read
Lubricants
- Lubricants are the excipients which are used in tablet formulation to reduce the friction between the product and the parts of the machine.
- Lubricants play a vital role during the tablet compression process where they are helpful to prevent sticking and picking.
- Lubricants reduce friction in dies and help with smooth ejection of tablets after compression without any sticking & picking defect.
- Lubricants are of two types, one is known as hydrophilic lubricant and the other is hydrophobic lubricant.
Example of lubricants
The most commonly used lubricant in tablet formulation is magnesium stearate, which is hydrophobic, and another one is sodium stearyl fumarate, which is hydrophilic.
Other examples of lubricants are as,
- Stearic acid
- Calcium stearate
- Mystric Acid
- Poloxamer
Note
The lubricants must always be used after sieving to increase the surface area, and the blending time with lubricants must be 3 to 5 minutes.
Detailed Article
Glidants
Glidants are the excipients which are used in tablet formulation to reduce the interparticle friction, and by reducing the interparticle friction they increase the flow of powder or granules.
Glidants are also known as flow enhancers or flow promoters, and these are added in the formulation to enhance the flow of product from the hopper to the feeder & and to ensure weight uniformity.
If glidants are not properly added in the tablet formulation, various defects like rat holing or weight variation are observed.
Examples Of Glidants
- Aerosil
- Talc
Also Read
Detailed Article on tablet glidants
Flavourants
- Flavourants or flavours are added in tablet formulation to mask the unpleasant or bitter taste.
- These are also known as flavouring agents and are added in chewable, dispersible or effervescent tablets.
- Flavours are volatile in nature, so these are added after the drying stage to take their maximum benefits.
Examples of Flavours
- Banana flavour
- Cherry flavour
- Strawberry flavour
Colouring Agents
Colours are added in tablet formulation for a number of reasons, including the masking of non-uniform colour or API or excipients, for brand identity and to prevent the chances of mix-up.
Colours may be of the following types
- Lakes
- Dyes
- Inorganic
- Natural
Lakes are the colours which are not soluble in water.
Dyes are water soluble and are not preferred to be used where heat is applied as they migrate due to evaporation of water.
Example of colours
- FD&C red
- FD&C blue
- Iron oxide red
- Iron oxide black
- Ponceau 4RS
- Quinoline yellow
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