Imaging drug delivery to skin with coherent raman scattering microscopy

Coherent Raman scattering microscopy is a new technique allowing high-resolution 3D imaging of the skin, with chemical contrast obtained based on Raman scattering. This technique is label-free and, unlike conventional microscopy techniques, does not rely on fluorescent probes, which are not good models for drug substances because of their different physicochemical properties and dissimilar skin penetration kinetics. Unlike other techniques such as tape stripping, coherent Raman scattering microscopy is non-destructive. The penetration pathway(s) of the drug and excipients from a topical vehicle can be visualised independently, and the ‘metamorphosis’ of an applied formulation at the surface of the skin can be imaged in real time.