Evaluation expérimentale de l'hydratation et du pouvoir occlusif in vivo et in vitro d'excipients lipophiles et de leurs émulsions phase huile continue.

Synopsis A study was carried out on three water in oil emulsions and their respective oil-phases, petrolatum, liquid paraffin and sweet almond oil, in order to compare their occlusive properties and thus their influence on cutaneous hydration. An in vitro method using 'Patel'cells in a water-saturated atmosphere at controlled temperature enabled, in the first instance, the various emulsions and their oil-phases to be classified according to their permeability to water vapour. The results are in order of increasing degree of occlusion: sweet almond oil, liquid paraffin and petrolatum. In in vivo studies on human volunteers, the influence of the application of the same substances on transepidermal water loss (TEWL) and cutaneous hydration was measured with an evaporimeter and a corneometer, in a temperature and humidity-controlled room. Measurements were performed on the flexor side of the forearm after sodium lauryl sulphate 5% insult on six subjects at times of 0, 30, 120 and 270 min. The different oils, used pure, increased the hydration by an occlusive effect, and this was described by measurements of TEWL. On the other hand, after using the emulsions, the increase in hydration noted does not appear to involve an occlusive mechanism.