In situ permeation study of drug through the stratum corneum using attenuated total reflection Fourier transform infrared spectroscopic imaging

Abstract

Infrared (IR) spectroscopy is one of the most chemically specific analytical methods that gives information about composition, structure, and interactions in a material. IR spectroscopy has been successfully applied to study the permeation of xenobiotics through the skin. Combining IR spectroscopy with an IR array detector led to the development of Fourier transform infrared (FTIR) spectroscopic imaging, which generates chemical information from different areas of a sample at the microscopic level. This is particularly important for heterogeneous samples, such as skin. Attenuated total reflectance [corrected] (ATR)-FTIR imaging has been applied to measure, in situ, the diffusion of benzyl nicotinate (BN) through the outer layer of human skin [stratum corneum (SC)]. In vitro experiments have demonstrated the heterogeneous distribution of SC surface lipids before the penetration of a saturated solution of BN. Image analysis demonstrated a strong correlation between the distribution of lipids and drugs, while ethanol appeared to be homogenously distributed in the SC. These results show the ability of ATR-FTIR imaging to measure simultaneously the affinities of drug and solvent to the lipid-rich and lipid-poor skin domains, respectively, during permeation. This information may be useful in better understanding drug-diffusion pathways through the SC.

Applications of FTIR Spectroscopic Imaging in Pharmaceutical Science

“…It has also been shown that ATR-FTIR imaging provides information on the swelling of the stratum corneum as a function of humidity. This approach was also used to image the penetration of liquid ethanol into the skin [77] and showed good potential for studying the transdermal delivery of drugs [78,79].…”

FT‐IR Imaging in ATR and Transmission Modes: Practical Considerations and Emerging Applications

“…The methodology described has also been applied to study the diffusion of drugs across porcine [93] and human skin [94]. The human skin study was conducted in vitro with skin obtained from the abdomen of human cadavers.…”

Imaging Analysis Enables Differentiation of the Distribution of Pharmaceutical Ingredients in Tacrolimus Ointments

“…The ATR FT-IR imaging could measure the affinity of benzyl nicotinate and solvent to the lipid-rich and lipid-poor skin domains, respectively, during permeation. 19 Although these techniques nondestructively obtain structural information without sample preparation, two-dimensional (2D) imaging ( x , y plane imaging) is insufficient to measure the accurate size and shape of droplets dispersed in semisolid formulations.…”