The skin penetration enhancement mechanism of n-methylpyrrolidone

N-methylpyrrolidone (NMP) is one of the most studied chemical penetration enhancer as its use in semisolid preparations since the early 1980s. Nevertheless, contrasting results are reported in literature and its penetration enhancement mechanism of NMP has been debated in a large number of papers. With a view to getting deeper insight into the mechanism by which NMP enhances the passive diffusion of a drug through the stratum corneum, this work investigated the possible interactions between NMP and human stratum corneum and two model drugs by combining experimental techniques with molecular dynamics (MD) simulations. Propranolol and hydrocortisone were selected as model drugs since their passive diffusion through the skin resulted influenced or unaffected by NMP, respectively.