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Impact of a pH 5 Oil-in-Water Emulsion on Skin Surface pH - PubMed

Impact of a pH 5 Oil-in-Water Emulsion on Skin Surface pH

Theresa Fürtjes et al. Skin Pharmacol Physiol. 2017.

Abstract

Background: Human skin surface has a physiologically acidic pH (pHss). In cases of increased pHss, the acidity of the skin can be restored by topical formulations. We tested a pH 5 oil-in-water (O/W) emulsion for pHss regeneration and stabilization.

Methods: We performed 2 experiments with 10 female study subjects in each. In both experiments, 2D imaging with luminescent sensor foils was used to determine pHss. Alkalization was reached by washing the volar forearm with a soap bar and warm running tap water for 20 min. Experiment 1: after defining the baseline pHss, we alkalized the respective area and measured pHss over a duration of 5 h, while applying emulsion every hour. Experiment 2: study subjects used the emulsion twice daily for 1 week. Then, pHss was measured before and after 5 min of washing a treated and an untreated area on the volar forearm.

Results: (1) 5 h after alkalization, the treated arm showed a significantly lower pHss than the untreated one (5.87 ± 0.03 vs. 6.05 ± 0.03); (2) after washing, the treated area had a significantly lower pHss than controls (6.13 ± 0.03 vs. 6.27 ± 0.05).

Conclusions: The tested pH 5 O/W emulsion seems to improve regeneration and stabilization of pHss.

Keywords: Acidification; Epidermal barrier; Human skin; Topical application; pH value.

© 2017 The Author(s) Published by S. Karger AG, Basel.

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Figures

Fig. 1
Fig. 1

Impact of a pH 5 O/W emulsion on skin surface pH (pHss). Pseudocolor images (100 × 100 pixels) of pHss 2D luminescent sensor foil measurements recorded with the imaging system VisiSens (PreSens GmbH) and processed with the imaging software VisiSens AnalytiCal 2 (PreSens GmbH). a Untreated left volar forearm (n = 10, age 25.2 ± 2.7 years). b Treated right volar forearm (n = 10, age 25.2 ± 2.7 years).

Fig. 2
Fig. 2

Short-term effect of pH 5 O/W emulsion on skin surface pH (pHss). Comparison: pHss of the untreated left (continuous line) and the treated right (dashed line) volar forearm of 10 healthy female volunteers before and during 5 h hours after washing both arms for 20 min with water and soap and applying pH 5 O/W emulsion to the right volar forearm every hour after the measurement. On the treated right volar forearm, pHss was significantly lower at 3, 4, and 5 h compared to pHss values on the untreated left volar forearm (n = 10, age 25.2 ± 2.7 years, triplicates, mean ± SEM). * p < 0.05, ** p ≤ 0.001, t test.

Fig. 3
Fig. 3

Long-term effect of pH 5 O/W emulsion on skin surface pH (pHss). Comparison: pHss on the untreated left and the treated right volar forearm before and after 5 min of washing the skin with water and soap. Previously to the measurement, the volunteers had used pH 5 O/W emulsion twice a day for 1 week. Approximately 8-10 h passed between the last application (the same morning) and the measurements, depending on the daily routine of the study subjects. While there was no significant difference in the pHss baseline values, a significant difference could be observed after the washing procedure, when pHss was significantly lower on the treated right volar forearm than on the respectively untreated left volar forearm (n = 10, age 22.7 ± 1.3 years, triplicates, mean + SEM). w/o, without pH5 O/W emulsion (untreated left volar forearm); w, with the application of pH 5 O/W emulsion twice a day for 1 week (treated right volar forearm); ns, no significant difference could be found. * p < 0.05, t test.

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