Skin optical clearing enhancement with penetration enhancer azone using spectroscopy and optical coherence tomography

In order to find a non-invasive way to improve the efficacy of skin optical clearing with topically applied optical clearing agents (OCA), we evaluated the effect of azone (R) (epsilon-Laurocapram) as a chemical penetration enhancer on optical clearing of intact skin in vitro. Fresh porcine skin with topical application of glycerol (G) mixed with water-soluble azone (A) was investigated using near-infrared spectroscopy and optical coherence tomography (OCT). Light transmittance at 1276 nm increased by 41% and diffuse reflectance at 1066 nm decreased by 29% at 60 min after treatment with 40%G5%A on a spectrophotometer with an internal integrating sphere. 40% glycerol with addition of azone was a more effective optical clearing agent than 40% and 80% glycerol. 60%G/5%A led to a 2-fold increase in achievable OCT imaging depth and a 2.2-fold increase in light intensity reflected off the underneath needle surface after 60 minutes in the OCT in-depth reflectance profiles. In conclusion, skin optical clearing with the topical application of glycerol was markedly enhanced by water-soluble azone. Skin permeation enhancing effect of azone accounts probably for the skin clearing enhancement.