Basic topical dermatological substances.
Treatment modalities for skin disease can be broadly categorized into medical therapy (topical and systemic treatments) and physical therapy (e.g. cryotherapy, phototherapy, photodynamic therapy, lasers and surgery).
Topical treatments directly deliver treatment to the affected areas and this reduces systemic side effects. It is suitable for localized and less severe skin conditions. They consist of active constituents which are transported into the skin by a base (also known as a ‘vehicle’). Examples of active ingredients are steroids, tar, immunomodulators, retinoids, and antibiotics. The common forms of base are lotion (liquid), cream (oil in water), gel (organic polymers in liquid, transparent), ointment (oil with little or no water) and paste (powder in ointment).
Basic topical substances include:
I. POWDERS
Inert powders may be mixed with active agents (antifungals) to deliver therapy. They provide a cooling effect, prevents friction, absorbs moisture. They are prescribed for lesions in moist or intertriginous areas. They are not used in oozing dermatoses due to crust formation. They can organic (starch) or inorganic (zinc oxide, lanolin)
II. LIQUIDS
Liquid vehicles include:
- Baths and soaks - are used when therapy must be applied to large areas, such as with extensive contact dermatitis or atopic dermatitis.
- Foams - are alcohol or emollient-based aerosolized preparations. They tend to be rapidly absorbed and may be favored in hair-bearing areas of the body.
- Solutions - are ingredients dissolved in a solvent, usually ethyl alcohol, propylene glycol, polyethylene glycol, or water. Solutions are convenient to apply (especially to the scalp for disorders such as psoriasis or seborrhea) but tend to be drying. They have cooling effect, soothing and antipruritic.
- Lotions - are water-based emulsions. They are easily applied to hairy skin. Lotions cool and dry acute inflammatory and exudative lesions, such as contact dermatitis, tinea pedis, and tinea cruris.
- Gels - are ingredients suspended in a solvent thickened with polymers. Gels are often more effective for controlled release of topical agents. They are often used in acne, rosacea, and psoriasis of the scalp.
III. OILS AND OILY SUBSTANCES
- Liquid-oil combination creams are used for moisturizing and cooling the skin
- Liquid-oil combination ointments are usually more potent than creams and are commonly used for lesions with crusts or scales