Medicated, solid dosage forms intended for insertion into body cavities (rectum, vagina, or urethra), where they melt, soften, or dissolve to exert local or systemic effects.
Suppositories
Inserted into rectum
Bullet-shaped, 32 mm long, ~2 g (adult), half for infants
Local (hemorrhoids, laxatives) or systemic (analgesics, antiemetics)
Suppository
Inserted into vagina
Globular, oviform, or cone-shaped; 3–5 g
Used as contraceptives, antiseptics, antibiotics, hormonal therapy
Vaginal Suppository (Pessary)
Inserted into urethra
Slender, pencil-shaped; Males: 3–6 mm × 140 mm (4 g), Females: half length/weight
Local antibacterial or anesthetic action (e.g., urethritis)
Urethral Suppository (Bougie)
Relief of pain, itching, inflammation; laxative effect
Glycerin suppository (laxative), hemorrhoidal preparations
Local Action
Drug absorption via rectal veins bypassing portal circulation
Indomethacin, Ergotamine tartrate, Ondansetron
Systemic Action
Evacuation may enhance absorption; diarrhea, tumors hinder it
- Colonic content
Lower hemorrhoidal veins bypass portal system (avoids 1st pass)
- Circulation route
Rectal fluids are near neutral (pH 7–8)
- pH & buffering capacity
Drug must balance solubility in base and rectal fluids
- Lipid-water solubility
Smaller size = faster dissolution and absorption
- Particle size
Must melt or dissolve at body temp and release drug efficiently
- Nature of base
Example: Theobroma oil (cocoa butter)
Melts at body temperature (30–35 °C)
Must not be overheated (>35 °C) → polymorphic changes alter melting point
Oleaginous (Fatty) Bases
Vaginal: 70% glycerin, 20% gelatin, 10% drug; Urethral: 20% glycerin, 60% gelatin, 20% drug
Translucent, resilient, slowly dissolves in mucous secretions for prolonged release
Hygroscopic → must be wetted with water before use
A. Glycerinated Gelatin
Mixture of PEGs (various molecular weights)
Nonirritating, water-miscible, stable, dissolves slowly (not melt)
Provides prolonged release
B. Polyethylene Glycol (PEG)
Fatty + water-soluble combination (e.g., Polyoxyl 40 stearate)
Modified release and compatibility
Often used for special formulations
C. Miscellaneous Bases
Oldest and simplest; mix grated cocoa butter + drug → hand-roll cylinders
Avoids heating; useful for heat-sensitive drugs
- Hand Rolling
Grated base + drug mixture compressed into molds
Requires mold calibration and density factor knowledge
- Compression Molding
Base melted → drug dissolved/dispersed → poured into molds and cooled
Most common; lubricate molds with mineral oil (esp. glycerinated gelatin)
- Fusion Molding
Ratio comparing drug and base density for accurate substitution
Aspirin DF in cocoa butter = 1.3 → 0.3 g aspirin replaces 0.23 g base
Density Factor (DF)
Calculates base displaced by drug
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=
100
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f=
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Dosage Replacement Factor (f)
Determines base needed by volume difference
12 mL mold – 2.8 mL drug = 9.2 mL base (× density)
Occupied Volume Method
Uses two-step casting to determine density factor and base weight
Useful for unknown DF drugs
Double Casting Technique
melts; PEG → dissolves; Glycerinated gelatin → dissolves slowly
Cocoa butter
