Learning Objectives

• Introduction to suppositories and their classification with examples
• Classification of suppository bases with the merits and demerits

Suppositories are unit solid preparations, which may contain one or more active medicaments intended for insertion into the body cavities other than mouth. They are normally used for local action or systemic absorption of the active ingredient. They usually melt, soften, or dissolve at body temperature. They may be inserted into rectum, vagina, urethra, nose or ear cavity.

Advantages of Suppositories

1. Suppositories are extensively used as a mechanical aid for bowel evacuation, which produces its action by either irritating the mucous membrane of the rectum (e.g., glycerol and bisacodyl) or by mechanical lubrication.
2. Suppositories may be used for local action. Examples are zinc oxide for soothing effect, cinchocaine and benzocaine as local anesthetic, bismuth subgallate, hamamelis extract, and tannic acid as astringents and hydrocortisone and its acetate for anti-inflammatory activity.
3. Suppositories are a reliable and alternative mode of administration of drugs that irritate the gastrointestinal tract, cause vomiting, are destroyed by the hepatic circulation or are destroyed in the stomach by pH changes, enzymes.

Types of Suppositories

1. Rectal suppositories: These are the preparations meant for introduction into the rectum for their local or systemic effect. They are tapered at one or both ends and usually weigh about 2g. The rectal suppositories meant for children are smaller in size with a weight of 1 g.
2. Vaginal suppositories (Pessaries): They are semisolid bodies meant for introduction into vagina. They are larger than rectal suppositories and vary in weight from 3g to 6g or more. They may be conical, rod shaped or wedge shaped and are exclusively used for their local action.
3. Urethral suppositories (Urethral bougies): They are meant for introduction into the urethra. They weigh between 2 g and 4 g with length 25 inch. They are very rarely used and should be sterile.
4. Nasal suppositories (Nasal bougies): They are meant for introduction into nasal cavity. They are similar in shape to urethral bougies and are prepared with glycero-gelatin base.
5. Ear cones (Aurinaria): They are miniature bodies meant for introduction into the ear. Theobroma oil is used as a base; these are prepared in a urethral bougies mold and cut according to the required size.

Properties of an Ideal Suppository Base

1. Melt at body temperature or dissolve or disperse in body fluids
2. Release the medicament readily
3. Retain its shape during handling, transportation and storage
4. Nontoxic and nonirritant to the mucous membrane
5. Compatible with any added medicament or additives
6. Stable if heated above its melting point
7. Easily available and economical
8. Easily moldable and should not adhere to the mold
9. Pharmacologically inert

Types of Suppository Bases

The following are the different types of suppository bases:

1. Fatty or oleaginous bases
2. Water-soluble or water-miscible bases
3. Emulsifying bases