Purpose: Application of external heat using a heating pad over buprenorphine transdermal system, Butrans® has been shown to increase systemic levels of buprenorphine in human volunteers. The purpose of this study was to perform in vitro permeation studies at normal as well as elevated temperature conditions to evaluate the correlation of in vitro data with the existing in vivo data.
Methods: In vitro permeation tests (IVPT) were performed on human skin from four donors. The IVPT study design was harmonized to a previously published clinical study design and skin temperature was maintained at either 32 ± 1 °C or 42 ± 1 °C to mimic normal and elevated skin temperature conditions, respectively.
Results: IVPT studies on human skin were able to demonstrate heat induced enhancement in flux and cumulative amount of drug permeated from Butrans® which was reasonably consistent with the corresponding enhancement observed in vivo. Level A in vitro-in vivo correlation (IVIVC) was established using unit impulse response (UIR) based deconvolution method for both baseline and heat arms of the study. The percent prediction error (%PE) calculated for AUC and Cmax values was less than 20%.
Conclusions: The studies indicated that IVPT studies performed under the same conditions as those of interest in vivo may be useful for comparative evaluation of the effect of external heat on transdermal delivery system (TDS). Further research may be warranted to evaluate factors, beyond cutaneous bioavailability (BA) assessed using an IVPT study, that can influence plasma exposure in vivo for a given drug product.
Keywords: buprenorphine; drug permeation, heat; in vitro – in vivo correlation; temperature.
© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.