Evaluation of the efficacy of a lip care cream for dry lips using a new method of evaluating skin physiological functions

We studied the use of "Nov® Lip Care Cream UV" in 50 subjects with lip dryness for 4 weeks to assess humidity retention and shading of lips. The study subjects were selected from patients with atopic dermatitis, infantile dry dermatitis, and photoallergy, who visited Fujita Health University Hospital, Rikako's Clinic of Dermatology, and Kobe University Hospital between November 2010 and May 2011. At the start and end of the trial, we measured the moisture content in the horny layer and the volume of transepidermal water loss from the lip skin. Further, to evaluate skin physiological functions, we measured the number of nucleated cells and levels of tumor necrosis factor (TNF-α) and thymic stromal lymphopoietin (TSLP) in horny layer cells collected by tape stripping. Forty-seven patients out of 50 were evaluated, and 3patients discontinued the use of the cream because of individual preferences. In regards to adverse events, 1 patient observed mild scaling and sclerosis of the lip skin, but continued cream usage. After 4 weeks of cream usage, we observed that dryness, scale, cracking, erythema, and vertical wrinkles were improved significantly. Although no significant changes were observed in the horny layer moisture content and volume of transepidermal water loss, which was measured using conventional equipment, we observed a significant decrease in the number of nucleated cells and TNF-α, and TSLP levels in the horny layer cells. These results suggest that "Nov® Lip Care Cream UV" improves cutis symptoms in dry lips. Additionally, we confirmed that horny layer analysis using tape stripping is useful for the evaluation of skin physiological functions in lips, where accurate measurements of the moisture content and volume of water loss are difficult because of their irregular shape, elasticity, and their involvement in pulmonary respiration.