Basics of medical therapy
The treatment of skin disease includes topical, systemic, intralesional, radiation and surgical modalities. Specific treatments are detailed below. First is an overview of dermatological therapies.
Topical therapy
Topical treatment has the advantage of direct delivery and reduced systemic toxicity. It consists of a vehicle or base, which often contains an active ingredient (Table 1).
| Drug | Indications | Pharmacology |
|---|---|---|
| Corticosteroids | Eczemas, psoriasis, lichen planus, discoid lupus erythematosus, sunburn, pityriasis rosea, mycosis fungoides, photodermatoses, lichen sclerosus | Mode of action is through vasoconstrictive, anti-inflammatory and antiproliferative effects; medication is available in different strengths; side-effects need to be considered |
| Antiseptics | Skin sepsis, leg ulcers, infected eczema | Chlorhexidine, benzalkonium chloride, silver nitrate and potassium permanganate are used |
| Antibiotics | Acne, rosacea, folliculitis, impetigo, infected eczema | Chlortetracycline, neomycin, bacitracin, gramicidin, polymixin B, sodium fusidate and mupirocin; resistance and sensitization are problems Metronidazole is used for rosacea |
| Antifungals | Fungal infections of the skin, Candida albicans infections | Nystatin, clotrimazole, miconazole, econazole, terbinafine, ketoconazole, sulconazole and amorolfine |
| Antiviral agents | Herpes simplex, herpes zoster | Aciclovir, penciclovir |
| Parasiticidals | Scabies, lice | Benzyl benzoate, permethrin and malathion for scabies; malathion, permethrin and phenothrin for lice – applied as a lotion or shampoo |
| Coal tar | Psoriasis, eczema | Presumed anti-inflammatory and antiproliferative effects; available as creams, shampoos and in paste bandages |
| Dithranol | Psoriasis | Antiproliferative effects; available as creams, pastes and ointments |
| Vitamin D analogues | Psoriasis | Calcitriol, calcipotriol and tacalcitol inhibit keratinocyte proliferation and promote differentiation |
| Keratolytics | Acne, scaly eczemas | Salicylic acid, benzoyl peroxide and tretinoin |
| Retinoids | Acne, psoriasis | Isotretinoin (acne), tazarotene (psoriasis) |
| Topical immunomodulators (calcineurin inhibitors) | Atopic eczema (and off-licence use in other diseases) | Tacrolimus and pimecrolimus |
Vehicles are defined as follows:
Lotion. A liquid vehicle, often aqueous or alcohol based, which may contain a salt in solution. A shake lotion contains an insoluble powder (e.g. calamine lotion).
Therapeutic properties of the vehicle
Lotions evaporate and cool the skin and are useful for inflamed or exudative conditions, e.g. for wet wraps (p. 37). The high water content of a cream means that it mostly evaporates; it is also non-greasy and easy to apply or remove. Ointments are best for dry skin conditions such as eczema. They rehydrate and occlude, but being greasy are difficult to wash off and are less acceptable to patients than creams. Pastes are ideal for applying to well-defined surfaces, such as psoriatic plaques, but are also hard to remove.
