A new paradigm in dermatopharmacokinetics - Confocal Raman spectroscopy

Confocal Raman spectroscopy (CRS) is a novel approach which has been used to determine stratum corneum thickness and to profile endogenous skin components. However, the utility of this technique for probing drug disposition in vivo has not been explored to date. In this paper we report the use of CRS to investigate the fate of ibuprofen after application from simple formulations which were previously investigated using the tape-stripping approach. Ibuprofen was prepared in propylene glycol (PG) and propylene glycol/water (PG/H2O) solutions. The formulations were then applied to the volar aspect of the forearm of human volunteers. The results confirmed that ibuprofen distribution profiles in the stratum corneum were comparable to previously published data from tape stripping experiments. We propose CRS as a non-invasive method for dermatopharmacokinetic evaluation of topical pharmaceutical formulations.