How to Prepare Suppositories?

1. Hand Mould Suppositories:

This is the oldest and simplest method of preparing suppositories. A skilled person is required for the preparation of suppositories.

General process for preparation of suppositories is as follows:

(a) Mix measured quantity of medicinal substances with sufficient quantity of theobroma oil.

(b) Triturate and, if required, soften with diluted alcohol and rub until a smooth paste is formed.

(c) Add remaining quantity of theobroma oil and add wool fat for consistency.

(d) When the mass becomes plastic by vigorous kneading of the pestle quickly remove from the mortar with a spatula.

(e) Transfer with spatula to a piece of filter paper and keep in hands during the kneading and rolling procedure.

(f) Roll the mass by quick rotating movements of the hands and immediately place on a pill tile.

(g) Rolling the mass on the tile with a flat board forms a cylindrical suppository.

(h) Cut in pieces by spatula.

(i) Give the shape by rolling one end on the tile with a spatula.

(j) Pack in butter paper or in proper container and store in cool place.

2. Compression mould suppositories (Cold compression)

(a) Mix theobroma oil and drug.

(b) Mixture is forced into a mould under pressure, using a wheel-operated press.

(c) Mould is removed, opened and replaced.

(d) On large-scale cold-compression machines are hydraulically operated by water- jacketed cooling and screw fed.

3. Fusion or melt mould suppositories

(a) Drug is dispersed or dissolved in a melted suppository base.

(b) Pour the mixture into suppository moulds and allow cooling in ice bath.

(c) Finished suppositories are removed by opening the mould.

(d) Various types and sizes of moulds are available for preparation of suppositories. Moulds are made of aluminum alloys, brass or plastic and are available with from six to several hundred cavities.

4. Automatic mould Machine

All filling, ejection, and mould cleaning operations are fully automatic. The output of a typical rotary machine ranges from 3500 to 6000 suppositories per hour. The suppository mould is lubricated by brushing or spraying and then filled to a slight excess. Excess material is removed after the mass gets solidified and collected for re-use. All heating and cooling systems are fully automatic.

Suppositories are usually formulated on weight basis. The medicament replaces the portion of base having same density as that of theobroma oil. If the drug substance is heavier, it will replace a proportionally smaller amount of theobroma oil.

Example 1

Prepare six suppositories containing 0.1 g tannic acid in each suppository.

Density of tannic acid is 1.6 as compared with cocoa butter.

Weight of blank suppositories = 2.0 g

Cocoa butter replaced by drug = 0.1/1.6 = 0.062 g

Cocoa butter required for one suppository = 2.000 – 0.062 = 1.938 g

Actual weight of one suppository = 1.938 + 0.10 = 2.038 g

Weight of cocoa butter for 8 suppositories (take excess weigh of 2 suppositories as required) = 1.938 x 8 = 15.504 g

Weight of tannic acid for 8 suppositories (take excess weigh of 2 suppositories as required) = 0.10 x 8 = 0.80 g

Total weight of all suppositories = 15.504 + 0.80 = 16.304 g

Example 2

Prepare 0.1 g tannic acid 6 suppositories using polyethylene glycol as base. Density factor of cocoa butter is 1.6 and density factor of polyethylene glycol is 1.25.

Weight of polyethylene glycol suppository = 1.75

Cocoa butter replaced by drug = (0.1/1.6) x 1.25 = 0.078 g

Polyethylene glycol required for one suppository = 1.750 – 0.078 = 1.672 g

Actual weight of one suppository = 1.672 + 0.10 = 1.772 g

Weight of polyethylene glycol for 8 suppositories (take excess weigh of 2 suppositories as required) = 1.672 x 8 = 13.376 g

Weight of tannic acid for 8 suppositories (take excess weigh of 2 suppositories as required) = 0.10 x 8 = 0.80 g

Total weight = 13.376 + 0.80 = 14.176 g

Displacement Value of Medicaments

The quantity of medicament that displaces one part of cocoa butter is called displace ment value. The volume of particular suppository mould is uniform but fill weight will vary according to the density of medicaments as compared with cocoa butter with which the mould was calibrated.

Determination of Displacement value

Weight of six suppositories of theobroma oil or any other base = a g

Weight of six suppositories containing, say 40 percent of drug(s) = b g

Calculate weight of theobroma oil = 60 / 100 x b = c g

Calculate drug(s) = 40/100 x b = d g

(a – c) g = the weight of theobroma oil displaced by d g of drug substances

Displacement value of the medicament = d / (a – c)

Displacement Values (DV) of Solid Medicaments

Packaging and Storage

Suppositories are packaged in partitioned boxes or in tightly closed screw-capped glass container or wrapped individually in aluminium foil. In large scale production suppositories are wrapped individually or separately in foil packs. Candy wrapping is the more familiar aluminium foil or PVC polyethylene strip. Low melting point suppositories should be store in cool place and theobroma oil suppositories should be stored in refrigeration.