Suppositories: Definition, Types, advantages, and disadvantages
Definition
A suppository is a solid dosage form that is inserted into the rectum (rectal suppository), vagina (vaginal suppository), or urethra (urethral suppository), where it dissolves or melts and exerts local or systemic effects. Suppositories are used to deliver medications that act both systemically and locally.
Classification of Suppository bases
1. Oleaginous bases:
Theobroma oil or cocoa butter was introduced as a base in 1852 and has been one of the most widely used bases. It satisfies most of the criteria of an ideal suppository base but it melts at 32°C i.e., below the body temperature.
Overheating alters its physical characteristics and it has a tendency to adhere to the mold when solidified. It may exist in 4 crystalline states.
γ Form: This form is obtained by suddenly cooling the melted mass to 0 °C. Its melting point is 24°C..
β Form: This form is obtained when cocoa butter is melted at 35 to 36°C and slowly cooled. It melts at 18 to 23°C.
β’ Form: It reverts back to (3 forms and melts at 34 to 35°C.
γ Form: It is obtained by pouring a cool (20°C) cocoa butter into a container before it is
solidified and cooled at deep-freeze temperature. It melts at 18°C
2 . Aqueous bases
- Glycero – gelatin:
It is a mixture of glycerin and water made into a stiff jell by the addition of gelatin. The proportion of gelatin can be varied according to the intended use of the preparation.
Gelato-glycerin bases dissolve in the body fluids liberating contained medicaments Gelato- glycerin Mass BP contains 14% gelatin, 70% glycerin and water. USP formula contains 20% gelatin together with 70% of glycerin.
- Different mixtures of polyethylene glycols are marketed under the trade names of Postonals, Carbo waxes, and Macrogols.
3. Emulsifying bases
Massa Esterinum, Witepsol, and Massupol are the trade names under which the emulsifying bases are marketed. Massa Esterinum is a mixture of the mono-, di- and triglycerides of the fatty acids having the formula C11H23COOH to C17H35COOH. Witepsol bases consist of hydrogenated triglycerides of lauric acid with added monoglycerides. These are available in 9 grades. Massupol consists of glyceryl esters namely lauric acid and the addition of a very small quantity of glyceryl monostearate. All these bases are free from the drawbacks of cocoa butter and don’t require any mold lubricant.
Advantages of Suppositories
- Avoid first-pass metabolism
- Introduce drugs into the body
- Does not cause nausea and vomiting due to gastric irritation in case of oral therapy
- Used before surgery since oral therapy is restricted
- Beneficial for patients suffering from severe vomiting
- Can be administered to unconscious patients
- Can be used as a targeted drug delivery system
- Localized action with reduced systemic distribution
- Get to the site of action with a lower dose reducing systemic toxicity
- Highly beneficial in hemorrhoids or vaginal infections
- Prolonged drug action achieved
Disadvantages of Suppositories
- Mucosal irritation
- Patient compliance
- Erratic and undesired absorption
- Placement too high into the rectum may lead to first-pass metabolism
- Installation may trigger defecation reaction
- GI state affects absorption:
- Diarrhea& disease states affect absorption
F Y D Pharm & S Y D Pharm Notes, Books, Syllabus, PDF, Videos
F Y D Pharm & S Y D Pharm Notes, Books, Syllabus, PDF, Videos
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