Читать книгу pH of the Skin: Issues and Challenges - Группа авторов - Страница 18

The importance of the acid character of the skin is well documented. Deviations from the physiological norm – whether causative or as a result of disturbance – entail some sort of skin barrier impairment. Under normal conditions, an ingenious buffering system in the skin ensures a perpetual normalization of the acid character of the skin.

Right from the very beginning of research in the field, researchers discussed opportunities and limitations to shape the acid character of the skin to protect the skin and to accelerate barrier recovery, to maintain, or to enhance barrier integrity. With the introduction of skin cleansers in the 1950s, the awareness for the importance of the acid character of the skin reached large parts of the population. The metaphor “acid mantle” played a major role in popularizing skin cleansers.

More recently, the benefits of targeted skin acidification have become clinically evident and the use of topical preparations with reduced pH (direct acidification) is being recommended. The currently prevailing formulation concepts for direct acidification are based on a reduced pH of the hydrophilic product phase in combination with a buffer with a sufficiently high buffering capacity. Important issues related to formulation composition (acids), buffering systems used, or the buffering capacity of product and product dosing have so far not been systematically investigated. Incontinence-associated dermatitis or atopic dermatitis is a medical and a highly relevant skin condition causing a great level of affliction that urgently needs treatment options. Because of these indications, products for targeted skin acidification may therefore offer new therapeutic options.

A matter of some concern is that the quantification of the acid character of the skin is technically very delicate and standardization and validation still incomplete. The existing guidance requires further work. Furthermore, many existing publications report incompletely the experimental conditions.

The term “acid mantle” was coined by those who first recognized the importance of the acid character of the skin. The physiologic role of the acid skin surface was thought to be a protective mechanism against invading organisms. Hence, it seemed reasonable to allocate protection to an easy and a conceivable term such as “mantle.” Since then, our understanding of the skin pH has tremendously broadened. The acid character and its changes within the skin help to orchestrate epidermal differentiation and corneocyte shedding. Today, the acid character of the skin is recognized as a key requisite for healthy skin. Against this background, it is still legitimate to keep this metaphor even 90 years after its creation.