2 research outputs found
A Multiscale Study on the Penetration Enhancement Mechanism of Menthol to Osthole
Menthol is a widely used penetration
enhancer in clinical medicine
due to its high efficiency and relative safety. However, details of
the penetration enhancement mechanism of menthol on the molecular
level is rarely involved in the discussion. In this work, the penetration
enhancement (PE) mechanism of menthol is explored by a multiscale
method containing molecular dynamics simulations, in vitro penetration
experiments, and transmission electron microscopy. Osthole is chosen
to be the tested drug due to its common use in external preparations
and because it often accompanies menthol as a PE in the preparations.
The results show that menthol in each testing concentration can impair
the lipid packing of stratum corneum (SC) and promote osthole permeating
into SC, and the penetration promoting effect has an optimal concentration.
At a low concentration, menthol causes the bilayer to relax with a
reduction in thickness and increment in the lipid headgroup area.
At a high concentration, menthol destroys the bilayer structure of
SC and causes lipids to form a reversed micelle structure. The penetration
enhancement mechanism of menthol is characterized mainly by the disruption
of the highly ordered SC lipid in low concentrations and an improvement
in the partitioning of drugs into the SC in high concentrations. The
results can provide some assistance for additional studies and applications
of menthol as a penetration enhancer
Using molecular simulation to understand the skin barrier
Skin's effectiveness as a barrier to permeation of water and other chemicals rests almost entirely in the outermost layer of the epidermis, the stratum corneum (SC), which consists of layers of corneocytes surrounded by highly organized lipid lamellae. As the only continuous path through the SC, transdermal permeation necessarily involves diffusion through these lipid layers. The role of the SC as a protective barrier is supported by its exceptional lipid composition consisting of ceramides (CERs), cholesterol (CHOL), and free fatty acids (FFAs) and the complete absence of phospholipids, which are present in most biological membranes. Molecular simulation, which provides molecular level detail of lipid configurations that can be connected with barrier function, has become a popular tool for studying SC lipid systems. We review this ever-increasing body of literature with the goals of (1) enabling the experimental skin community to understand, interpret and use the information generated from the simulations, (2) providing simulation experts with a solid background in the chemistry of SC lipids including the composition, structure and organization, and barrier function, and (3) presenting a state of the art picture of the field of SC lipid simulations, highlighting the difficulties and best practices for studying these systems, to encourage the generation of robust reproducible studies in the future. This review describes molecular simulation methodology and then critically examines results derived from simulations using atomistic and then coarse-grained models.Drug Delivery Technolog