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Optimizing topical therapy (Proceedings)

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Aug 01, 2011

Topical therapy is an important symptomatic and complimentary treatment option in the management of various skin diseases. Canine skin is often more sensitive than is human skin due to anatomical and physiological differences, including differences in the thickness of the stratum corneum, skin pH and hair follicle density which can facilitate cutaneous penetration of active ingredients. The active ingredients penetrate the skin through the intercellular spaces (lipophilic molecules), through the epidermal cells (ion compounds). Several formulations such as ointments, creams, lotions shampoos, spot-on, etc. are available and may include many active ingredients. For successful topical management the selection of the appropriate formulation and active ingredient is important. However, the selection may depend on concurrent therapy, the animal's temperament owner compliance, and the concentration and potential side effects of the active ingredients. Client communication is important and should underline the great value of medicated shampoos for the treatment of skin diseases.

Ointments, creams and gels

Creams and ointments are a mixture (emulsion) of oil and water. They are usually used on dry skin, and not on oozing (exudative) areas. Gels are composed of a thixotropic (gel at rest, but fluid when agitated) base (usually containing propylene glycol), pass through the hair coat to the skin and are less messy and occlusive than creams and ointments. These bases are used as vehicles for many agents:

Topical glucocorticoids

Have anti-inflammatory and antipruritic properties as well as antiproliferative and immunosuppressive effects. These formulations are useful for localized lesions (e.g., cheilitis, blepharitis, pododermatitis, nasal lesions, pyotraumatic dermatitis, lick granuloma). Common glucocorticoids found are: dexamethasone, betamethasone and hydrocortisone.

Localized skin atrophy and comedo formations can be seen with excessive long-term application.

Immunomodulators

Tacrolimus (Protopic 0.1%; Astella), a calcineurin inhibitor has been shown to be effective in the treatment of localized lesions of vasculitis, auto-immune diseases (e.g. discoid lupus, pemphigus erythematosus), and canine atopic dermatitis.

Antibiotics

Formulations containing fusidic acid and mupirocin (Bactoderm; Pfizer) are useful for treating localized lesions of pyoderma.

Antifungals

Human products containing azole derivatives, nystatin or amphotericin B can be used on localized lesions of dermatophytosis, Malassezia dermatitis or candidiasis.