Diluents are the most important ingredients used in solid dosage forms to increase the bulk volume. Diluents have no pharmacological activity but are required for formulation development to give dosage form a proper dimension and weight.
The minimum requirements for tablet size are more than 2-3 mm and tablet weight should be more than 50 mg for easy compression and handling of tablets.
Other Names
The following are synonymous of diluents
- Fillers
- Bulking agents
Explanation
If the potency of an API is 5 mg then it means that 5 mg is the weight of API and if our target weight is 100 mg & after adding all other excipients like binders, disintegrants, lubricants,glidants etc the required weight of the tablet is not achieved then this gap is filled by a excipient which is known as diluent.
Example
Suppose as we discussed previously our target tablet weight is 100 mg but after the addition of active pharmaceutical ingredients and all other excipients except diluent, it becomes 60 mg then the remaining 40 mg is achieved by the addition of Diluent.The diluent may be used up to 80% depending on the formulation of dosage form.
The diluent used should not interact with active pharmaceutical ingredients or with other excipients used and should not promote microbial growth in the formulation.
Classification of Diluents
Diluents are classified into the following categories depending on chemical nature and solubility.
Organic Diluents
- Lactose
- Starch
- Pregelatinised starch
- Sucrose
- Mannitol
Inorganic Diluents
- Calcium phosphate dibasic
- Calcium phosphate Tribasic
Water Soluble
Following are examples of water-soluble excipients
- Lactose
- Mannitol
- Sucrose
Water Insoluble
Following are water-insoluble excipients
- Starch
- Cellulose
- Calcium Phosphate
Also Read
- Granulation in pharmaceutical industries.
- Sound level requirements for working in pharmaceuticals.
- Purified water supply system.
- Classification of Excipients.
- Role of mannitol in pharmaceutical products.
- Uses of Starch and modified starch in tablet manufacturing.
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