The Pharmaceutics and Compounding Laboratory
Preparation of Suppositories

Laboratory Procedure

BE SURE TO USE THE SAME MOLD THROUGHOUT THE EXPERIMENT.

A. Calibration of Suppository Molds with Cocoa Butter

Use the following procedure to calibrate the mold with cocoa butter.

  • Clean mold with soap and water.

  • Dry the mold.

  • Have the mold at room temperature.

  • Apply a light film of glycerin to the cavities with a cotton applicator.

  • Melt approximately 30 g of cocoa butter on a steam bath or hot plate but NOT more than 35°C.

  • Remove the mixture from the heat and fill the mold cavities. Overfill cavities until there is a slight overflow of cocoa butter onto the surface of the mold. This is necessary to allow for shrinkage during cooling.

  • Allow the cocoa butter to cool at room temperature for 30 minutes. If it is not solidified at that time, put in a refrigerator for an additional 30 minutes. Do not freeze.

  • Carefully remove the excess with a hot spatula or knife scarped flat across the top surface of the mold.

  • Separate mold by removing the three wing nuts from the ends of the brass screws. Then rest entire assembly on the brass posts and apply pressure to lower half of mold.

  • CAUTION: Never open mold by prying at parting line with knife, spatula, or other instrument. This will damage the matching mold faces which have been accurately machined to give a tight seal and eliminate breakage.

  • Remove suppositories.

  • Clean entire mold thoroughly with soap and water. Dry completely.

  • Using only perfect specimens, weigh the suppositories and record the total weight. Calculate the average suppository weight.
    Mold # __________
    Total weight for ____ suppositories = _________ g
    Average weight for one suppository = _________ g
    Mold lubricant used _____________________
    Inspection of Final Product _____________________

B. Calibration of Suppository Molds with Glycerinated Gelatin Base

Glycercinated Gelatin Suppositories have the following proportions of glycerin, gelatin, and water. Use 75 g of the suppository base for this calibration exercise.

Ingredients Percentage Weight Basis Amt./Vol. to measure
Glycerin
70%
__________ g
_________ ml
Gelatin
20%
__________ g
_________ g
Purified Water
10%
__________ g
_________ ml

To calibrate the mold with glycerinated gelatin suppository base:

  • Clean mold with soap and water.

  • Dry the mold.

  • Have the mold at room temperature.

  • Lubricate the mold with light mineral oil.

  • Mix the glycerin and water together and heat on a steam bath or hot plate for 5 minutes. Gently stir in the gelatin to avoid incorporating air in the mixture. After the gelatin has been added, continue heating for another 40 - 50 minutes. Do not allow the temperature to get above 90 - 95°C, as the color will darken.

  • Remove from the heat and allow the mixture to cool near the melting point before pouring into the mold.

  • Overfill the cavities in the mold, cool at room temperature for 30 minutes, and then place in a refrigerator 15-20 minutes if the suppositories have not completely congealed.

  • Carefully remove excess with a hot spatula or knife. Remove suppositories from mold.

  • Using only perfect specimens, weigh the suppositories and record the total weight. Calculate the average suppository weight.
Mold # __________
Total weight for ____ suppositories = _________ g
Average weight for one suppository = _________ g
Mold lubricant used _____________________
Inspection of Final Product _____________________

C. Calibration of Suppository Molds with PEG Base

PEG Base Suppositories have many different PEGs and proportions. For this calibration exercise, use 50 g of the following proportions of PEG 3350 and PEG 400.

Ingredients Percentage Weight Basis Amt./Vol. to Measure
PEG 400

40%

__________ g
_____________ ml
PEG 3350
60%
__________ g
_____________ g

To calibrate the mold with PEG suppository base:

  • Clean mold with soap and water.

  • Dry the mold.

  • Have the mold at room temperature.

  • Do not lubricate the mold.

  • Melt 30 g of PEG 3350 first on a steam bath or hot plate, then reduce the heat and mix in 20 g of PEG 400.

  • Remove from the heat and allow the mixture to cool near the melting point before pouring into the mold.

  • Overfill the cavities in the mold. Let stand at room temperature 30 minutes, or until solid. Do not put in refrigerator or freezer.

  • Carefully remove excess with a hot spatula or knife; then remove the suppositories from the mold.

  • Using only perfect specimens, weigh the suppositories and record the total weight. Calculate the average suppository weight.
Mold # __________
Total weight for ____ suppositories = _________ g
Average weight for one suppository = _________ g
Mold lubricant used ____________________
Inspection of Final Product ______________________

D. Fusion Molding - Using an Estimated Density Factor

Using the PEG suppository base above, prepare the following prescription (prepare for 8 suppositories, but dispense only 6).

                        Jacquelyn Hyde, MD              Rx# 61501
                        123 Upendown Road
                        Nowhere, NC 27000
Phone:  555-1234                               DEA# PS0079411

Name:   Jerry Atrick                         Date:   Today  
Address:  105 N.Duke St., Durham, NC 27707   Phone: 123-4567

      Rx
              Aspirin  200 mg
              M.Ft.  D.T.D. supp.  #6
              Sig:  1 q 12 hours     
  Refills:  2

  Jacky Hyde,M.D.                                        
  Product selection permitted         Dispense as written

 

Calculations:

  1. 1. Based on your data from Parts A & C above, calculate the ratio of PEG base relative to cocoa butter.

  2. 2. Based on the density factor of aspirin in cocoa butter, calculate the amount of PEG base that would be displaced by 200 mg of aspirin per PEG suppository.

  3. 3. Based on information in 2. above, estimate by calculation the density factor of aspirin in PEG base.

Write the procedure you will use to compound the prescription:

Mold # __________    
Weight of Aspirin for 8 suppositories _________ g  
Weight of base needed for 8 plain suppositories _________ g  
Weight of base displaced by Aspirin _________ g  
Weight of base needed for Aspirin suppositories _________ g  
Weight of PEG 400 needed for Aspirin suppositories _________ g _________ ml
Weight of PEG 3500 needed for Aspirin suppositories _________ g  
Mold lubricant used _____________________  
Inspection of Final Product _____________________  

 

 

E. Double Casting Method - Experimentally Determining the Density Factor

Make progesterone suppositories and calculate the density factor of progesterone in a PEG base (prepare for 12 suppositories, but dispense only 10).

                        Jacquelyn Hyde, MD              Rx# 61502
                        123 Upendown Road
                        Nowhere, NC 27000

Phone:  555-1234                              DEA# PS0079411

Name:   Jerry Atrick                         Date:   Today  
Address:  105 N.Duke St., Durham, NC 27707   Phone: 123-4567

      Rx
             Progesterone    200 mg
             M.Ft.  D.T.D. supp.  # 10
             Sig:  Insert 1 suppository vaginally q HS for 10 days
  Refills: 1

  Jacky Hyde,M.D.                                        
  Product selection permitted         Dispense as written

Procedure:

      Step 1. Calibrate the mold: (continue to use the mold you have used throughout the exercise)

        Fill the mold with PEG base:
        PEG 400    20 g (17.8 ml)
        PEG 3350  30 g

      Step 2. Determine the average weight of plain PEG suppositories _________ g

      Step 3. Double Casting of progesterone suppositories:

        First Casting:
        Use sufficient base for 12 suppositories:
        • Progesterone: 200 mg × 12 = 2.4 g

        • PEG base: use about 70% of needed PEG base: (Step 2) g × 12 × 0.7 = _______ g

            PEG 400: (______) g × 0.4 = ______ g, ________ ml (density = 1.125 g/ml)
            PEG 3350: (______) g × 0.6 = _______ g

          Compounding procedure:
          1. Melt PEG 3350 first to about 55-60 °C. Reduce the heat and mix in the PEG 400.
          2. Add progesterone through a 40 mesh sieve in portions with constant stirring to prevent clumps.
          3. After all the progesterone has been wetted and dispersed, turn off heat.
          4. Allow the melt to cool (continue stirring).
          5. Pour into mold only partially filling each cavity. DO NOT FILL ANY ONE CAVITY.
          6. Fill the remaining space in each cavity with additional PEG base.
          7. When the suppositories are congealed, remove them from the mold.

          Determine the average weight of these first casting suppositories ___________ g

        Second Casting:
        • Remelt the suppositories (steam bath may be used to melt PEG off sides of beaker).
        • Pour into mold to make 10 suppositories.

Calculate the density factor of progesterone in PEG base suppositories.

    Average weight of plain PEG suppository (from mold calibration) ____________ g
    Weight of progesterone in each suppository ___0.20_____ g
    Average weight of medicated suppository (from first casting) ____________ g
    Weight of PEG base in medicated suppository ____________ g
    Weight of PEG base displaced by progesterone ____________ g

 

Inspection of Final Product _________________________