The ideal suppository base should
• Nontoxic and nonirritating to mucous membranes.
• compatible with a variety of drugs.
• The base melts or dissolves in rectal fluids/body cavities.
• The base should be stable on storage; it should not bind or otherwise interfere with the release or absorption of drug
Commonly used suppository bases are: cocoa butter, cocoa butter substitutes (primarily vegetable oils modified by esterification, hydrogenation and/or fractionation), glycerinated gelatin, hydrogenated vegetable oils, mixtures of polyethylene glycols of various molecular weights, and fatty acid esters of polyethylene glycol.
Suppository bases are classified into two major categories
1. Fatty suppository bases
|S. No.||Fatty base||Properties|
|1.||Theobroma oil / coca butter||– Most suitable for rectal suppository|
– Mixture of Glyceryl ester of different unsaturated Fatty acids.
|2.||Emulsified Thepbroma oil||–|
2. Hydrophilic suppository base
Hydrophilic (Water-loving) suppository base includes two categories.
- Water soluble Bases
- Emulsifying Bases
A. Water-soluble Bases:
Water-soluble base favors more drug release from suppository than Fatty/oil base. Example
- Glycero Gelatin base :- Gelatin + glycerine + water
- PEG – Carbowaxs or macrogols & Polyglycols
B. Emulsifying Bases:–
- Massa estarinum
Preparation of Suppositories
Click below on the respective link to read more about evaluation of suppositories
- Uniformity of weight
- Melting point range
- Liquification or softening time test for rectal suppositories
- Breaking test
- Dissolution testing
- Solid FAT Index (FAT)
Liquefaction testing provides information on the behavior of a suppository when subjected to a maximum temperature of 37◦C. The test commonly used is Krowczynski’s method, which measures the time required for a suppository to liquefy under pressures similar to those found in the rectum (approximately 30 g) in the presence of water at 37◦C. In general, liquefaction should take no longer than about 30 minutes.
New Trends of Suppositories
Pessaries: Pessaries are meant for introduction into the vagina.
- Compressed Tablet Suppository – recommended for vaginal use
- Rectal / Urethral Suppositories – melt/ soften
- Vaginal Suppositories are compressed tablets and designed to disintegrate in body fluids. So Rectal suppositories usually are not compressed as tablets because the amount of liquid in the rectal cavity is inadequate for tablet disintegration.