Displacement value & its calculations

• 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:

Calculating the Displacement Value (D.V.)

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.