Principles of Topical Therapy

Abstract

Dermatologists have the good fortune to work on the most accessible organ of the body. Many inflammatory and neoplastic conditions can be effectively managed using the wide range of locally applied physical or pharmacological modalities that are available. The latter are the subject of this chapter, which reviews the pharmacological treatments used topically, i.e. by application to the surface of the skin. Some of these are time‐honoured treatments that have been used for a century or more, whilst others belong to the ever‐expanding range of newer and increasingly potent agents constantly being developed and formulated for topical use. Topical treatment offers the potential to achieve high concentrations of a drug in the skin with minimal exposure of other organs. This can greatly increase efficacy and also safety relative to systemic administration. When side effects do occur, they are most likely to take the form of localized reactions.

Use of topical therapies for pediatric psoriasis: A systematic review

“…Because of their anti‐inflammatory, immunosuppressant, and antiproliferative properties, topical steroids have been widely used for many years in the management of numerous skin diseases. The efficacy of topical steroids can be classified on a 4‐point scale as mild, moderate, potent, and very potent The most common side effects are found at application sites and include cutaneous atrophy, impaired wound healing, and exacerbation of infections and rosacea …”

“…Examples of topically used calcineurin inhibitors include formulations of tacrolimus and pimecrolimus, which have a mechanism of action that is similar to that of cyclosporine, but unlike cyclosporine, both of these agents have sufficiently low molecular weight to penetrate the stratum corneum . A notable advantage of these agents is that they do not induce cutaneous atrophy, even with long‐term application.…”

“…To avoid this adverse reaction, topical agents with a safer profile have been developed. Such formulations include calcitriol and calcipotriol (also known as calcipotriene) and have the benefit of not leading to any long‐term cutaneous atrophy and the disadvantage of causing local irritant reactions …”

“…The disadvantages of coal tar include the potential for irritancy, phototoxicity, and carcinogenicity. Even though many improved formulations (eg, creams and shampoos) have become available in recent years, none completely remove the tar's odor or the risk of staining …”

“…It offers a safe long‐term treatment because it is not known to cause carcinogenicity or systemic toxicity but causes local irritation and stains clothes and skin. Short‐contact applications (varying in length from 10 to 60 minutes) have been shown to be as effective as prolonged contact and facilitate self‐treatment at home …”