An insight into the n-methylpyrrolidone skin penetration enhancement mechanism

The current work aimed to provide an insight on the mechanism of N-methylpyrrolidone (NMP) as skin permeation enhancer. The possible influence of NMP vehicled both in water and mineral oil on the organization of human stratum corneum was investigated by ATR-FTIR spectroscopy. The enhancement ability of NMP in both vehicles was assessed by evaluating the in vitro permeation study of propranolol selected as model drug since its flux through human skin was not significantly influenced by vehicles (i.e. mineral oil or water). Finally, the possible interactions between drugs and NMP were investigated in silico by comparing the MD simulations of an optimized cubic box of NMP in presence of propranolol, lidocaine and hydrocortisone. The last two molecules were chosen as examples of drugs whose skin permeation is influenced (lidocaine) or unaffected (hydrocortisone) by NMP.