Suppositories | Definition, classification, advantage, disadvantage, preparation, testing

Definition of Suppository:

A suppository is a semi-solid dosage form used to deliver a drug by inserts into the body cavities (such as the rectum, vagina, etc.), and it melts at those areas to provide the therapeutic effect.

Uses of Suppositories:

• Suppositories are great for patients with constipation. There are various types of laxative suppositories like bisacodyl suppositories, glycerin suppositories, etc.
• Rectal suppositories are very useful for hemorrhoids and piles patients. It reduces swelling and discomfort.
• Vaginal and urethral suppositories are great for fungal infection in the vagina and urethra. (clotrimazole, miconazole, etc are used as a drug.)

Advantages of Suppository:

• It's easy to use for those patients, who are unable to take oral medication. (like unconscious patients, children)
• Increase the bioavailability of drugs.
• Very useful to get local effects.
• It avoids the first-pass metabolism.
• It provides rapid action.
• Best for vaginal and rectum fungal infection.

Disadvantages of Suppository:

• It can cause irritation in some patients.
• Some patients feel embarrassed.
• Preparation is complicated compared to liquid and tablets.
• Need low temperature to store.
• Very few drugs can be delivered by this type of dosage form.

Classification of suppositories:

There are 5 types of suppositories according to the route of administration

• Rectal suppositories
• Vaginal suppositories
• Urethral suppositories
• Nasal suppositories
• Ear suppositories

There are 4 types of suppositories in other dosages form

• Tablet Suppositories
• Layered Suppositories
• Coated Suppositories
• Capsule Suppositories

Tablet Suppositories:

Tablet Suppositories are prepared just like tablets in the compression method. It's used for the rectal and vaginal routes.

Layered Suppositories:

Layered suppositories are made with different drugs in different layers to avoid incompatibility between those drugs.

Coated Suppositories

Coated suppositories made with free unsaturated fatty acids, polyethylene glycol, etc. for their smooth lubricating properties.

Capsule Suppositories

Capsule suppositories are made with soft gelatin in various sizes and shapes. It is filled with solid, semisolid, and liquids drugs.

Suppository Bases:

Suppository bases are those materials that maintain their shape and solidity. There are various types of bases like theobroma oil, glycerogelatin base & polyethylene glycol, etc.

Types of Suppository Bases:

1. Oleaginous Bases or Oily Bases:

• Cocoa Butter
• Hydrogenated oils.

2. Hydrophilic Bases or Water Soluble Bases:

• Gelatin bases
• Polyethylene glycol

3. Emulsifying or synthetic Bases:

• Witepsol
• Massa estarinum
• Massuppol

Ideal Properties of Suppository bases:

• It should be non-irritant and non-reactive.
• It should melt at body temperature.
• It must maintain the proper shape and size.
• It should be stable in storage conditions.
• It should shrink sufficiently to remove mold.
• It should not interfere in the release or absorption of the drug.

Preparation methods of Suppositories:

1. Hand mold method or Hand rolling method
2. Compression mold (Cold compression) method
3. Fusion or melt mold method

4. Automatic mold method.

1. Hand mold method or Hand rolling method:

This is the oldest and easiest method of suppository preparation. In this type of method, the mixture of the drug and suppository bases are mixed together and rolled by hand to provide the shape of the suppositories. This method is not used now because it's a time-consuming process and quite difficult.

2. Compression mold (Cold compression) method:

The cold compression method is a very popular method of preparing suppositories. This method is heating is not required that's why it's applicable for thermolabile and insoluble drugs.

The ingredients are mixed with a suppository base. Then the prepared mass is placed power-operated compression machines. This method is not suitable for any base (glycerol gelatin base) in which melting is essential.

3. Fusion or melt mold method:

This is called the heat method. In this type of method, the drug is dispersed into the suppository base.

Before molding the mold is lubricated properly. Then the hot mixture of the suppository base and the drug is poured into the mold and colled into the ice bath then the suppositories are removed from the mold. Then the excess materials are removed from it.

This process is mostly used for dispensing purposes. Hope you already did it in your practical class.

4. Automatic mold method:

The automatic mold method is the fastest method for the bulk production of suppositories. All the processes from mixing, filling, ejection, and molding are totally automatic. Due to high-speed production, the production output 5000-10000 suppositories per hour. By automatic machine, the extra materials are collected and re-used after the solidification of the suppositories.

For automated production, a huge amount of raw materials and storage areas are required.

Suppository Molds: 

For small-scale production, each suppository molds have the capacity to produce 6 or 12 suppositories. Industrial or bulk production suppository molds are capable to produce thousands of suppositories in a single time.

Packaging of Suppositories:

Normally suppositories are packed one by one in plastic or aluminum foil. Most of the suppositories are stored in a cold place to maintain their proper size and shape. Refrigeration is required. In the case of polyethylene glycol suppositories, room temperature is enough for storage, and a refrigerator is not required.

Testing of suppositories:

Uniformity of weight test:

In this test, the weight measurement is done for those suppositories which are produced in the same mold. To maintain the uniformity of the weight.

Melting Range test: 

Macro-melting range: Here the time is measured that takes for the entire suppository to melt when immersed in a constant temperature (37 degrees Celcius) in the water bath.

Micro-melting range: Here the melting range is measured in capillary tubes for the oily or fat base only.