How do dermatological vehicles influence the horny layer?
Emulsifying agents in aqueous solution lead to dehydration of the horny layer of the epidermis and damage to the barrier. This is only partly true if emulsifying agents are constituents of emulsions. Water-in-oil (W/O) emulsions cause an improvement in the hydration of the horny layer and barrier function. In the case of an additional effect of wash solutions, a partial or complete abolition of the drying out and barrier-damaging effect of the wash solution results. Oil-in-water (O/W) emulsions without glycerol have no effect on the moisture of the horny layer or indeed increase it, but they lead to considerable damage to the barrier and irritation. In wash tests, they do not induce any protective effect. With micro-emulsions this is still more the case and, moreover, they can also lead to exsiccation. As a result of the addition of glycerol, the barrier-damaging effect can be abolished. Also in stress tests with wash solutions, the damage to the horny layer is reduced by glycerol-cont
