Influence of water dilution on percutaneous absorption of N-vinyl-2-pyrrolidone in vivo and ex vivo in rats and ex vivo in humans.

N-vinyl-2-pyrrolidone (NVP) is mainly used as a monomer in the production of polyvinylpyrrolidone or copolymers. Percutaneous absorption is an important source of exposure in the work environment. However, few studies have investigated this route of absorption. In this study, percutaneous absorption of neat or aqueous NVP solutions was measured in vivo and ex vivo in rats, and ex vivo in humans. Penetration and absorption fluxes were very similar following in vivo exposure to neat NVP (0.54 and 0.43 mg/cm(2)/h, respectively). Exposing rats to a 50% aqueous solution of NVP increased both fluxes threefold (to 1.48 and 1.55 mg/cm(2)/h, respectively). Ex vivo, the absorption flux increased with solutions from 10 to 25% of NVP, reached a plateau (between 25 and 50% in rat, 25 and 75% in human) and then decreased with neat NVP. In vivo and ex vivo absorption fluxes measured using rat skin were similar, supporting the hypothesis that the ex vivo measurements were a good representation of what was observed in vivo. Thus, for humans, the ex vivo measurements are likely the same as would be determined in vivo.