Displacement value & its calculations
- S-1-Pharmaceutics I
- Feb 27
- 1 min read
Updated: Mar 2
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Displacement value (D.V.) is a crucial concept in the preparation of suppositories, particularly when using the fusion molding method.
It helps determine the amount of suppository base required to incorporate a specific amount of active pharmaceutical ingredient (API) while maintaining the desired weight of the suppository.
Key Concepts
Displacement Value (D.V.): The amount of suppository base displaced by a given amount of API.
It ensures proper dosage and uniformity in prepared suppositories.
Importance of Displacement Value
The displacement value is essential for:
Calculating the correct amount of suppository base needed.
Maintaining the intended weight and dosage of each suppository.
Ensuring uniformity across all suppositories.
Calculating the Displacement Value (D.V.)
Formula
Information Needed
Desired weight of each suppository (W)
Weight of API in each suppository (A)
Weight of base displaced by the API (B)
Calculating the Weight of the Base
Once the displacement value (D.V.) is known, the weight of the base required for each suppository can be calculated using the following formula:
This formula ensures accurate determination of the base quantity needed to prepare suppositories with the correct dosage and uniform weight.
Example
If you have:
Desired suppository weight (W) = 2 g
Weight of API in each suppository (A) = 0.5 g
Displacement value (D.V.) = 1.5
Then:
So, you will need 1.25 g of base for each suppository.
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