i -� '#. = I- (I) 'ta � i •.-4 (I) '#. = (.) I- 'ta � 100 80 60 40 20 WATER-HANDLING PROPERTIES OF VERNIX CASEOSA 657 a) --0- Vemix caseosa -A- W /0 emulsion ---0--- O/W emulsion 0 ,__ _ __.__ _ __.__ _ ___,�-�-�------.........---------' 0 20 40 60 80 100 120 140 160 180 200 Time (minutes) 100 b) 80 ---o-Vernix ----- HIPE #I ____..,_ HIPE #II 60 ---.- HIPE # III -+- HIPE#IV -+- HIPE#V � HIPE#VI 40 - HIPE#VII 20 .__ _ _.___.....__ _ _._ _ _._ _ _._ _ __. __ ,__ _ _.___.....___....J 0 20 40 60 80 100 120 140 160 180 200 Time (minutes) Figure 1. (a-b) Water release profiles of native vernix, typical emulsions, and high internal phase W/O preparations (mean ± SE, n = 3). profiles replotted based on initial water content of 100 percent weight. The difference in water release rate between native vernix and HIPE number VII is not statistically significant. WATER VAPOR TRANSPORT Table III presents the water vapor transport (WVT) values of standard emulsions, and HIPEs compared to that of native vernix. WVT is reported as gram of water evaporating

658 JOURNAL OF COSMETIC SCIENCE 120 ---o-- Vernix caseosa ---0--- W /0 emulsion --6:----- O/W emulsion -- HIPE # VII 0 0 20 40 60 80 100 120 140 160 180 200 Time (minutes) Figure 2. Water release profile of vernix, typical emulsions, and selected W/O HIPE based on 100% initial water content. Table III Water Vapor Transport of Vernix Compared to That of Typical Emulsions, Vernix-Like Lipid-in-Water Emulsions, and W /0 HIP Es Material N-terface® + Vernix (25 mg/cm2) N-terface® + W/0 emulsion (25 mg/cm2) N-terface® + O/W emulsion (25 mg/cm2) N-terface® + Formulation I (25 mg/cm2) N-terface® + Formulation II (25 mg/cm2) N-terface® + Formulation III (25 mg/cm2) N-terface® + Formulation IV (25 mg/cm2) N-terface® + Formulation V (25 mg/cm2) N-terface® + Formulation VI (25 mg/cm2) N-terface® + Formulation VII (25 mg/cm2) * Mean ± SD, n = 3. Measurements were made at 22°-24°C and 37-38% RH. WVT (g/ m 2 /h)* 19.3 ± 4.9 2.6 ± 0.2 72.0 ± 3.0 17.3 ± 1.7 18.9 ± 1.3 20.1 ± 1.3 20.0 ± 0.4 13.5 ± 0.4 15.1±0.6 21.5 ± 3.0 through a square meter of film of test material per hour (g/m2/h). Vernix at the film thickness of 25 mg/cm2 has a WVT of 19.2 ± 4.9 g/m2/h. WVTs of W/O and O/W emulsions at the same film thickness were 2.6 ± 0.2 g/m2/h and 72.0 ± 3.0 g/m2/h, respectively. Most of the HIPEs were comparable to native vernix in water permeability. HIPE formulations II, III, IV, and VII provided WVTs within 11 % of that reported for native vernix. Figure 3 summarizes the WVTs of standard commercial emulsions and selected HIPEs compared to the WVT of native vernix. DISCUSSION Premature infants have an ineffective epidermal barrier ( 4) and lack a surface coating material of vernix caseosa. As consequence, the premature skin is highly permeable to