Suppositories
Suppositories are solid dosage forms designed for insertion into body cavities such as the rectum, vagina, or (occasionally) the urethra, where they melt, dissolve, or soften to release their active ingredients for either local or systemic effects.
Characteristics of Suppositories
1. Shape and Size:
Rectal suppositories: Torpedo-shaped, approximately 2 cm in length.
Vaginal suppositories: Oval or globular.
Urethral suppositories: Slender and cylindrical.
2. Base Material:
Must melt or dissolve at body temperature (~37°C).
Examples: Cocoa butter (theobroma oil), polyethylene glycol, glycerinated gelatin.
3. Drug Release:
Local effects: Treat hemorrhoids, inflammation, or infections.
Systemic effects: Drugs absorbed through the rectal mucosa bypass first-pass metabolism (e.g., analgesics, antipyretics).
Advantages of Suppositories
1. Avoidance of First-Pass Metabolism: Drugs administered rectally can bypass the liver.
2. Alternative Route: Suitable for patients unable to swallow oral medications (e.g., unconscious or vomiting patients).
3. Localized Treatment: Provides direct action at the site of insertion (e.g., anti-inflammatory or anti-hemorrhoidal).
Limitations of Suppositories
1. Patient Compliance: Insertion may cause discomfort or embarrassment.
2. Variable Absorption: Drug absorption through rectal mucosa can be inconsistent.
3. Storage Sensitivity: Suppositories may soften or melt at high temperatures.
Components of Suppositories
1. Active Ingredient: Provides the therapeutic effect.
Examples:
Local: Hydrocortisone (anti-inflammatory).
Systemic: Paracetamol (antipyretic).
2. Base: Supports drug release and absorption.
Examples: Cocoa butter, PEG, or glycerin.
3. Additives: Enhance stability or performance.
Stabilizers, preservatives, or surfactants.
Types of Suppositories
1. Rectal Suppositories: Used for local conditions like hemorrhoids or systemic effects like pain relief.
Example: Dulcolax (bisacodyl) for constipation.
2. Vaginal Suppositories: Used for treating infections, dryness, or as contraceptives.
Example: Clotrimazole for fungal infections.
3. Urethral Suppositories: Used less frequently, often for local conditions like urethral infections.
Example: Alprostadil (treat erectile dysfunction).
Preparation of Suppositories
1. Molding Method: Drug and base are melted and poured into molds, then cooled.
2. Compression Method: Active ingredients and base are compressed into the desired shape.
Pessaries
Pessaries are solid dosage forms intended for insertion into the vagina, where they melt or dissolve to release the active ingredient for local action. They are primarily used for gynecological conditions.
Characteristics of Pessaries
1. Shape and Size: Oval, cone-shaped, or globular. Typically larger than rectal suppositories.
2. Base Material: Must dissolve or melt at vaginal temperature (~37°C).
Examples: Glycerinated gelatin or polyethylene glycol (PEG).
3. Drug Release: Designed for localized treatment within the vaginal cavity.
Advantages of Pessaries
1. Localized Action: High drug concentration at the site of action with minimal systemic absorption.
2. Non-invasive Administration: Does not require professional assistance.
3. Extended Retention: The vaginal cavity allows prolonged contact with the mucosa.
Limitations of Pessaries
1. Discomfort: Insertion may cause temporary discomfort.
2. Leakage: Dissolution of the base may lead to leakage, requiring the use of sanitary protection.
3. Storage Sensitivity: Similar to suppositories, they can melt or soften at high temperatures.
Components of Pessaries
1. Active Ingredient: Target specific vaginal conditions.
Examples:
Clotrimazole (antifungal for candidiasis).
Progesterone (for hormonal therapy).
2. Base: Supports drug dissolution or melting.
Examples: Glycerinated gelatin or PEG.
3. Additives: Improve formulation stability or enhance comfort.
Uses of Pessaries
1. Antifungal Therapy: Treat vaginal candidiasis (e.g., clotrimazole pessaries).
2. Contraception: Deliver spermicidal agents (e.g., nonoxynol-9).
3. Hormonal Therapy: Progesterone pessaries for luteal phase support in IVF.
Preparation of Pessaries
Similar to suppositories, they are often prepared using the molding method or by compression techniques.
Comparison: Suppositories vs. Pessaries
| Parameter | Suppositories | Pessaries |
| Site of Action | Rectum, vagina, urethra | Vagina only |
| Shape | Torpedo, globular, or cylindrical | Oval, cone-shaped, or globular |
| Purpose | Local and systemic effects | Localized vaginal action |
| Base | Cocoa butter, PEG, glycerinated gelatin | Glycerinated gelatin, PEG |
| Uses | Pain relief, constipation, infections | Vaginal infections, hormonal therapy |
Both suppositories and pessaries are effective dosage forms tailored for localized treatment and, in some cases, systemic effects. Suppositories have broader applications, while pessaries are specifically designed for vaginal administration. Their composition, design, and method of application ensure efficient drug delivery in conditions where oral or parenteral routes are unsuitable.
