Topical Treatment of Pruritic Skin Disease and the Role of Community Pharmacists

Itching, or pruritus, can be defined as an unpleasant sensation that evokes the desire to scratch. Pruritus is most commonly associated with a primary skin disorder such as atopic dermatitis (AD), psoriasis, etc., and can have a major impact on the quality of life of those patients. Itch-induced scratching can further damage the skin barrier, leading to a worsening of symptoms. For that reason, it is important to manage pruritus. Topical glucocorticoids are commonly the first-line therapy in the management of AD and psoriasis patients. We found that topical glucocorticoids induce pruritus in mice under certain conditions. Topical glucocorticoids may induce pruritus in a mouse model of allergic contact dermatitis via inhibition of prostaglandin (PG)D2 production in antigen-mediated activated mast cells in the skin. Additionally, topical glucocorticoids do not induce pruritus in healthy skin. These results indicate the importance of controlling skin inflammation to a healthy level by applying sufficient quantities of glucocorticoids to avoid glucocorticoid-induced pruritus. However, topical "steroid phobia" is common in Japan, and most patients apply inadequate amounts of topical glucocorticoids for this reason. This may cause glucocorticoid-induced pruritus in patients by prolonging the skin inflammation. We conducted a survey regarding community pharmacists' instructions on the application quantity of topical glucocorticoids and found that most community pharmacists have experienced inappropriate instructions concerning this point.