“…HEC is frequently used in the formulation of gels with mucous administration because it was demonstrated to be similar to the fertile cervical mucus [ 24 , 25 ]. On the other hand, HPMC is used as excipient in more than 80% of the pharmaceutical products with oral administration [ 26 ] and, unlike HEC, has the property of retaining water, structuring the gel in a particular manner without dehydrating the biological substrate when it gets in contact with [ 27 , 28 ], thus providing comfort feel in occlusive state of application. The flexibility and the elasticity of the polymeric films are ensured by plasticizers (e.g., polyethylene glycol, propylene glycol and polysorbates) which often can also act as permeation activators, when they breach into the corneous layer of the epidermis [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ].…”