Introduction
Topical formulations are applied directly to the skin.
- Advantages:
- Deliver higher drug concentration at the target site.
- Fewer systemic side effects.
- Disadvantages:
- Can be messy or time-consuming.
- May require multiple applications or products.
Each formulation contains an active ingredient (e.g., corticosteroid, antifungal) and a vehicle/base (e.g., cream, ointment, gel) designed to deliver the drug effectively.
Types of Formulations
Formulation | Key Features | Best For |
---|---|---|
Creams | Oil-in-water emulsions (approx. 50/50). Moisturising. Require preservatives. | Normal to dry skin |
Ointments | Greasy, semi-solid, occlusive (80% oil), water-free. No preservatives needed. | Dry, scaly skin |
Gels | Aqueous/alcoholic, often cellulose-based. Liquefy on contact. May contain preservatives/fragrances. | Oily/combination skin |
Lotions | Thicker than solutions, lighter than creams. Often water-based. | Oily skin, warm climates |
Patches | Adhesive systems for systemic drug delivery. Bypass first-pass metabolism. | Long-term, precise dosing |
Active Ingredients (Selected Examples)
Category | Purpose | Examples |
---|---|---|
Corticosteroids | Inflammation, itching (eczema, dermatitis) | Hydrocortisone, Clobetasol, Triamcinolone |
Antifungals | Tinea, candidiasis, fungal infections | Clotrimazole, Terbinafine, Nystatin |
Antibacterials | Impetigo, folliculitis, cellulitis | Mupirocin, Polymyxin B, Bacitracin |
Keratolytics | Exfoliation, acne, wart removal | Salicylic acid, Glycolic acid, Lactic acid, Podophyllotoxin |
Choosing the Right Formulation
Based on Skin Type
Skin Type | Recommended Formulation | Ingredients to Look For |
---|---|---|
Oily | Lightweight gels, water-based lotions | Hyaluronic acid, Glycerin |
Dry | Thick creams, ointments | Shea butter, Ceramides, Urea |
Sensitive | Hypoallergenic, fragrance-free creams | Aloe vera, Oatmeal |
Normal | Light non-greasy moisturisers | Balanced humectants/emollients |
Combination | Gel/lotion hybrids or mix by area | Varies |
Based on Skin Condition
Condition Type | Suggested Formulation |
---|---|
Wet/oozing lesions | Creams, lotions, drying pastes |
Dry/scaly skin | Ointments, oils |
Inflamed skin | Soaks → creams/ointments |
Cracked/sore skin | Bland preparations |
Palms/soles | Creams or ointments |
Hairy areas | Gels, foams, solutions |
Skin folds | Creams or lotions (not ointments) |
Mucosal areas | Non-irritating formulations |
Key Pharmacological Considerations
Factors Influencing Absorption:
-
Skin thickness: Thinner = greater absorption
-
Barrier integrity: Damaged skin absorbs more
-
Occlusion: Increases drug penetration
-
Lipophilicity & molecule size
-
Concentration & excipients
Special Populations:
-
Babies: Fragile barrier, immature organs — use with caution
-
Pregnancy/Breastfeeding: Avoid potentially teratogenic topicals (e.g., Podophyllin, 5-FU, high-strength salicylic acid)
Application Tip:
-
For best results, apply topicals to damp skin (within 3 minutes of bathing) to improve absorption and hydration.
Common Ingredients in Vehicles
-
Occlusives: Petrolatum, mineral oil (seal in moisture)
-
Humectants: Hyaluronic acid, glycerin (draw moisture in)
-
Emollients: Ceramides, shea butter (soothe and smooth)
-
Preservatives: Prevent bacterial/fungal growth
-
Enhancers: Propylene glycol, alcohol — may aid penetration
Summary
- Choose formulation based on skin type, condition, location, and patient preference.
- Know when to use emollient-rich ointments vs. lightweight lotions or gels.
- Topical corticosteroids are potent anti-inflammatory agents — use appropriate potency and avoid long-term use.
- Tailor treatment and base formulation to maximise therapeutic benefit while minimising irritation.
References
- DermNet NZ: Topical Formulations – https://dermnetnz.org/topics/topical-formulations
- Benson, H. A. E. (2012). Transdermal drug delivery – Current Drug Delivery
- British Association of Dermatologists – https://www.bad.org.uk
- NICE BNF Treatment Summaries – https://bnf.nice.org.uk
- Dr Alexis Granite – Choosing the Right Moisturiser – dralexisgranite.com
- Real Simple – Skincare Product Guide – realsimple.com