It works from the surface, in the dermis

A short, charged, water-loving chain does not cross a healthy outer skin barrier in quantity, and it is not meant to reach deep motor nerve endings. Its work happens in the upper skin, where repeated creasing drives the lines you see, and it is carried by the base it is blended into. This is why cosmetic use puts it in a leave-on cream or serum and why patches of dissolving microneedles have been used to carry peptides of this family further in.