Methods of Preparation, Displacement Value, Its Calculation and Evaluation of Suppositories : Pharmaguideline -->

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Methods of Preparation, Displacement Value, Its Calculation and Evaluation of Suppositories

Hand rolling method, Compression Mold method, Fusion or melt Mold method, Automatic Mold method, Displacement value of suppositories, calculations etc

Methods of preparation

Hand rolling method or hand Mold method
This is the easiest and oldest method of preparing a suppository. This method involves mixing the drug with suppository bases and then rolling by hand to provide the suppository shape. It is, however, quite a difficult and time-consuming process, which makes it not commonly used.

Compression Mold method (cold compression method)
Suppositories are generally prepared by using the cold compression method. Heating is not required with this method, which makes it applicable to both thermolabile and insoluble drugs. Suppositories are made by mixing ingredients with a base. Once the mixture is prepared, it is inserted into power-driven compression machines. A group of bases (glycerol gelatine base) in which melting is essential cannot be analyzed with this method.

Fusion or melt Mold method
This is done by heating the Mold. Dispersion of the drug into the suppository base is the strategy used in this method. The Mold needs to be properly lubricated beforehand. Before suppositories are removed from the Mold, the suppository base mixture that has been heated and poured into the Mold is immediately cooled in an ice bath. This is followed by removing any excess materials. Dispensation is the main function of this process.

Automatic Mold method
Suppositories can be manufactured in bulk the fastest using the automatic Mold method. The entire production process is fully automated, including mixing, filling, ejection, and molding. 5000-10000 pills suppositories are produced per hour as a result of the high-speed production. Automatic machines collect and reuse the leftover materials after the suppositories have solidified.

Raw materials and storage areas are needed in large amounts for automated production.

Displacement value of suppositories

One gram of suppository base can be displaced by one gram of drug if the displacement value is exceeded. Suppository bases are commonly made from Cocoa Butter or Theobroma oil. In traditional suppositories, one gram or two grams of the base are generally placed in a Mold to hold the suppositories. Molds have a fixed volume that can't change, i.e., the Mold volume remains constant. The addition of a drug or excipient to the base displaces some of the bases and takes up some space.


As a rule of thumb, the weight of the suppositories is equal to the amount of base (base + drug) as opposed to the weight of the suppositories themselves.

(100-X %) The required amount of base can be = b x (100-X) / 100 = C gm

In suppositories, there is a small amount of medicament present = b × (x / 100) = d gm

Replacement of drug with base in grams = a - c gm

Therefore, Displacement value = d / (a-c)

For example -

Is the displacement value of zinc oxide the same for suppositories containing 40% zinc oxide in theobroma oil?

Theobroma oil in one suppository is equivalent to 8 grams as 1 × 8 = 8 grams

A weight of 11.74 grams is obtained from 8 zinc oxide suppositories of 40% zinc oxide

In a bowl of 8 suppositories, theobroma oil is present in an amount of =

60/100 x11.74= 7.044 g

8 suppositories are included in the package of medications

40/100 x11.74=4.696 g

Replacement of 4.696 g of a drug by the base

8-7.044 =0.956 g

Displacement value =

= 4.696/0.956


= 5 approx.

Evaluation of suppositories

Suppositories Are Evaluated in Different Ways:

Test of appearance

There should be no differences in size or shape among the suppositories. The suppositories should have an elegant appearance. Cracks and pits can occur due to air being trapped in the molten mass. Examine each suppository separately for signs of air entrapment.

Breakage test (Test of physical strength)

The tensile strength of the bundles of suppositories is measured to assess their resistance to normal handling. Testing is conducted using an apparatus called a breaking test apparatus. There are two walls to this apparatus. This chamber pumps water through its walls. Suppositories are contained inside a disc in the inner chamber. It is connected by a rod. Alternatively, the end of the rod is made up of another disc that contains weights.

Test of dissolution rate

Dissolution of dosage forms occurs over an extended period in body fluid. It measures the rate at which the medication leaves the suppository. The dissolution rate can be determined using two different types of instruments. They are

Suppository dialysis cells - To further define the characteristics of lipophilic suppositories, suppository dialysis cells are used. Subsequently, modified flow-through cells are used to test lipophilic suppositories.

Stationary basket - Located in the stationary basket is a rotating paddle apparatus (USP dissolution test apparatus). Suppositories with hydrophilic properties are tested with a rotating paddle basket apparatus.

Test of melting range

A micro melting range is determined the same way as a macro melting range:

Macro melting range
The thermal stability of a suppository is measured by this parameter. Melting the suppository over a given period is carried out in an environment of constant temperature. A tablet disintegration apparatus is used for the test. Water is continuously poured over the suppository during the test. This is followed by a melting investigation.

Micro melting range
Capillary tubes are used to measure the melting range of a fatty base.

Liquefaction time (Softening)

The softening time refers to the time that it takes for the suppository to melt completely at a certain temperature. As a result of this test, the softening time of suppositories can be estimated, which describes the hardness of the basis.

The fabricated instrument was used to conduct a liquefaction time and temperature test. To test the pipette, a large-sized pipette was taken, with a narrow opening on one side and a large hole on the other. It was dipped in hot water maintained at 35°C with 0.2°C on the narrow end facing hot water. The suppository was gently pushed down the length of the pipette, starting at the broad end and continuing to the narrow end. It was then inserted so that a glass rod was resting on top of the suppository. A temperature of liquefaction was noted as the rods just came down, which represents the temperature of liquefaction. It is at the narrow end of the glass rod that the liquefaction time of the suppositories can be measured.
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