Definition: Ointments are semi-solid topical preparations intended for application on the skin or mucous membranes. They are typically greasy and contain a high proportion of an oily base. Ointments deliver therapeutic agents locally or systemically, protect the skin, and hydrate or lubricate the skin.
Characteristics of Ointments
1. Semisolid Consistency: Allows easy application and adherence to the skin.
2. Occlusive Nature: Forms a barrier, preventing water loss and aiding in wound healing or skin hydration.
3. Homogeneous: Uniform distribution of active ingredients.
4. Insoluble in Water: Generally hydrophobic, which limits water absorption.
5. Slow Drug Release: Ensures prolonged action at the site of application.
Types of Ointment Bases
1. Hydrocarbon (Oleaginous) Bases
Composition: Made from hydrocarbons like petrolatum or paraffin.
Properties:
Greasy and occlusive.
Non-water washable.
Examples: White petrolatum, Vaseline®.
Uses: Provides prolonged action, prevents moisture loss.
2. Absorption Bases
Composition: Hydrocarbon bases with the ability to absorb water.
Properties:
Allows incorporation of aqueous solutions.
Greasy and occlusive.
Examples: Hydrophilic petrolatum, lanolin.
Uses: Used for hydrophilic drug formulations.
3. Water-Removable Bases (Creamy Ointments)
Composition: Oil-in-water (O/W) emulsions.
Properties:
Water washable.
Non-greasy and aesthetically appealing.
Examples: Vanishing creams, hydrophilic ointments.
Uses: Preferred for cosmetic and easily removable applications.
4. Water-Soluble Bases
Composition: Polyethylene glycols (PEGs).
Properties:
Completely water-soluble and washable.
Non-greasy.
Examples: PEG ointments.
Uses: Delivering water-soluble drugs.
Formulation Components
1. Active Ingredient: The drug or therapeutic agent.
Example: Antibiotics (mupirocin), steroids (hydrocortisone).
2. Base: Determines the ointment’s consistency and properties.
Example: Petrolatum, lanolin.
3. Stabilizers: Enhance the stability of the formulation.
Example: Antioxidants like butylated hydroxytoluene (BHT).
4. Preservatives: Prevent microbial growth in water-containing bases.
Example: Methylparaben, benzyl alcohol.
5. Humectants: Attract moisture to the skin.
Example: Glycerin, sorbitol.
Advantages of Ointments
1. Prolonged Action: Sustained drug release.
2. Occlusive Effect: Retains moisture and promotes wound healing.
3. Non-Irritating: Suitable for sensitive or damaged skin.
4. Wide Range of Uses: Used for local, systemic, protective, and cosmetic purposes.
Disadvantages of Ointments
1. Greasy Nature: May stain clothes and feel unpleasant.
2. Poor Patient Compliance: Greasiness can deter usage.
3. Limited Drug Loading: Certain drugs may not be compatible with oily bases.
4. Low Drug Release Rate: Slow diffusion from the base.
Preparation Methods
1. Incorporation Method: The active ingredient is mixed into the base using geometric dilution.
Tools: Mortar and pestle, ointment slab.
2. Fusion Method
Components are melted and mixed together.
Suitable for bases with waxes and high melting point ingredients.
Process:
Heat the base until melted.
Add active ingredients.
Cool while stirring to ensure uniformity.
Evaluation of Ointments
1. Spreadability: Measured using a spreadometer. Indicates ease of application.
2. Consistency: Evaluated using penetrometry (hardness).
3. Drug Content Uniformity: Ensures even distribution of the active ingredient.
4. Viscosity: Measured using a viscometer.
5. Stability: Evaluated under various storage conditions to check for separation or degradation.
6. Irritancy Testing: Ensures the product is non-irritating to the skin.
Applications of Ointments
1. Local Action:
Example: Antibacterial ointments for infections.
2. Systemic Action:
Example: Hormonal ointments (e.g., testosterone).
3. Protective Use:
Example: Barrier ointments to prevent diaper rash.
4. Cosmetic Use:
Example: Emollients for skin hydration.
5. Wound Healing:
Example: Silver sulfadiazine for burns.
Examples of Ointments
Antiseptic: Betadine (Povidone-iodine).
Antibiotic: Neosporin (Bacitracin, Neomycin).
Corticosteroid: Hydrocortisone ointment.
Antifungal: Clotrimazole ointment.
Moisturizing: Petroleum jelly.
Ointments are an essential form of topical medication, offering sustained action and protective effects. Their formulation depends on the therapeutic requirement, patient preference, and drug properties. Despite some limitations, ointments remain indispensable in dermatology, cosmetology, and wound care.
