12. SUPPOSITORIES AND PESSARIES

Suppositories and Pessaries

Introduction to Suppositories:

Suppositories are solid medicated dosage forms intended for insertion into body cavities other than the mouth, such as rectum, vagina, and urethra, for local or systemic effects. The term derives from the Latin suppositus, meaning “to place under.” Rectal and urethral suppositories usually use bases that melt or soften at body temperature, whereas vaginal suppositories, also called pessaries, may be compressed tablets that disintegrate in body fluids.

Advantages of Suppositories:

Exert local effects on rectal mucosa.
Promote bowel evacuation.
Avoid gastrointestinal irritation.
Useful for unconscious patients and those unable to swallow oral medication.
Bypass first-pass metabolism for systemic drug absorption.
Suitable for babies, elderly, postoperative patients, and those with nausea or vomiting.

Disadvantages:

Patient acceptability can be limited.
Some drugs may be irritating or require large amounts unsuitable for suppositories.
Incomplete absorption may occur due to bowel evacuation.
Not suitable for patients with diarrhea.

Types of Suppositories:

Rectal suppositories: Usually torpedo-shaped, weighing about 2 g for adults, smaller for children. Used for systemic or local effects including analgesics and bowel evacuation.
Vaginal suppositories (Pessaries): Larger, often globular or conical, used primarily for local vaginal effects.
Urethral suppositories (Bougies): Pencil-shaped; males (4 g, 100-150 mm), females (2 g, 60-75 mm).
Nasal suppositories (Nasal bougies or buginaria): Made with glycerogelatin base, approx. 1 g and 9-10 cm long.
Ear cones (Aurinaria): Rarely used, often prepared using theobroma oil as base.

Ideal Properties of Suppository Bases:

Melt at body temperature or dissolve in body fluids.
Non-toxic, non-irritant, good appearance, compatible with drugs.
Easy to mold, stable to heat, retain shape during handling, and have stable storage properties.
Specific physicochemical values like acid value below 0.2, saponification value 200-245, iodine value below 7, and high water incorporation capacity.

Types of Bases:

Fatty bases: Including theobroma oil (cocoa butter), emulsified theobroma oil, hydrogenated oils.
Water soluble/miscible bases: Such as glycerogelatin, soap glycerin, polyethylene glycols.
Emulsifying bases: Commercially known as Massa Esterinum, Witepsol, Massupol; contain surfactants and melt at body temperature.

Methods of Preparation:

Hand rolling: Mixing and molding a plastic mass manually.
Compression molding: Forcing mixed mass into molds mechanically.
Fusion molding: Melting base, dissolving drug, pouring into molds, and solidifying.

Packaging, Storage, and Labeling:

Suppositories must be packed so that they don’t touch each other to avoid damage. Packaging includes foil, paper, or plastic strips. Store in cool places, preferably refrigerated. Label with clear instructions such as “STORE IN A COOL PLACE,” “FOR EXTERNAL USE ONLY,” and “NOT TO BE TAKEN ORALLY.”

Evaluation Tests:

Appearance, size uniformity, presence of cracks.
Breakage test for physical strength using apparatus measuring tensile force.
Dissolution rate testing for rate of drug release.
Melting range and liquefaction time to assess thermal behavior.
Uniformity of drug content across samples.
Drug uptake studies in vitro and in vivo.

Suppository Stability Issues:

Blooming: White powdery surface deposit during storage.
Hardening: Crystallization leading to hardness, affecting melting and drug absorption rates.

Pessaries:

Pessaries are vaginal suppositories, larger than rectal ones (4-8 g or more), molded in various shapes and often supplied with applicators for ease of insertion. They can also be vaginal tablets or capsules.

Pessaries may require moistening before insertion to reduce irritation. Storage is in cool places with appropriate wrapping to prevent moisture uptake.