Compounding Hotline

Q: Do you have a formulation for cocoa butter and 2% menthol topical or suppository?

A: This preparation could be used for topical use or for suppositories. The preparation will be a soft solid, molded by the pharmacist. The following method for suppositories may be adjusted to your mold size. Fattyblend or another fatty acid suppository material is preferable to cocoa butter for ease of handling. Fattyblendcan be used 1:1 instead of cocoa butter.

Ingredients 1 suppository

Menthol 2% 0.036 g

Fattyblend qs ad 100% (fatty acid blend) 1.784 g

Note: The common 2-cm³ suppository mold will contain, when filled, cooled, and trimmed to size, approximately 1.82 g of Fattyblend, of which 2% is 0.0364 g, or approximately 36 mg.

Density Factor (DF) calculation: The “5% rule” for dose forms permits estimating the DF ratio as 1:1, where total amount of added active ingredient(s) and excipient(s) is not more than 5% of the weight of the blank dose form, because the error will be well within acceptable limits for compounding (USP <795>). Here, 5% x 2 g = 0.100 g or 100 mg (mold size 2 cm³, water = 2 g). Therefore, the DFs of the Fattyblend and menthol may be considered as 1:1 and the Fattyblend replaced 1:1 with menthol. It is good practice to increase each ingredient in the formulation by 5% to 10% to allow for processing losses.

Method

1. Calculate the ingredients accurately.

2. Weigh/measure the ingredients.

3. Place the menthol in a ceramic or Wedgwood mortar and reduce it to a fine powder with the pestle. Cocoa butter or fatty acid blend will accommodate (emulsify) a small amount of ethanol to dissolve the menthol if you desire.

4. Melt the cocoa butter or fatty acid blend at approximately 55°C while performing step 3.

5. Combine the menthol powder or solution with the melted vehicle using a stirring motion, and pouring the menthol into the vortex.

6. Pour into molds, and allow it to cool at room temperature.

7.Package. Label: Keep in refrigerator/Do not freeze. PT

Mr. Erickson is director of professional affairs and director of professional services at Gallipot, a Fagron company.

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