Page 40 - Course Guide 2019

9.5 SUPPOSITORY

The formulation of suppository usually used the mould made based on the weight of cocoa
butter. The volume is fixed and uniform, thus if there is another ingredient(s) that will be added
in the formulation, a displacement value of the ingredient(s) will have to be considered in
calculating the amount of base (cocoa butter/witepsol/macrogol) needed. This is because the
density of the ingredient(s) added will cause the suppository to weigh differently although
having the same volume.

Displacement value is the number of parts by weight of the medication/ingredient that
displaces ONE part by weight of the suppository base. As an example, if the displacement
value of Drug A (DV) is 3, it means that 3 g of Drug A will displace 1 g of cocoa butter.

DV of drugs with reference to cocoa butter is as follows:

Drug DV Drug DV
Aminophylline 1.2 Opium 1.5
Aminopirin 1.5 Paraffin 1.0
Aspirin 1.2 Phenobarbitone 1.3
Benzoic acid 1.7 Phenol 1.0
Bismuth subgallate 3.0 Potassium bromide 2.5
Boric acid 1.7 Potassium iodide 5.0
Castor oil 1.0 Procaine 1.5
Chloral hydrate 1.5 Quinidine HCl 1.5
Cocaine HCl 1.5 Resorcinol 1.5
Codeine phosphate 1.2 Salicylic acid 1.5
Dimenhydrinate 1.5 Sodium barbitone 1.5
Diphenhydramine HCl 1.5 Sodium bromide 2.5
Galic acid 2.2 Sodium pentobarbitone 1.5
Hydrocortisone 1.5 Spermaceti 1.0
Hydrocortisone acetate 1.5 Tannic acid 1.8
Ichtammol 1.2 Water 1.0
Menthol 0.8 Zinc oxide 5.0
Morphine HCl 2.0 Zinc sulphate 3.0

The mould used for the preparation of suppositories needs to be lubricated before use,
especially when cocoa butter or glycero-gelatin is used as the base. This is important to
facilitate the removal of suppository from the mould upon freezing.

The lubricant for cocoa butter suppositories consist of a mixture of [soft soap 10g : glycerol
10 mL : alcohol 90% 50mL], whilst for glycerol-gelatin, liquid paraffin or any fixed oil can be
used as the lubricant (such as castor oil and arachis oil).