Extrapolation of systemic bioavailability assessing skin absorption and epidermal and hepatic metabolism of aromatic amine hair dyes in vitro

Extrapolation of systemic bioavailability assessing skin absorption and epidermal and hepatic... Approaches to assess the role of absorption, metabolism and excretion of cosmetic ingredients that are based on the integration of different in vitro data are important for their safety assessment, specifically as it offers an opportunity to refine that safety assessment. In order to estimate systemic exposure (AUC) to aromatic amine hair dyes following typical product application conditions, skin penetration and epidermal and systemic metabolic conversion of the parent compound was assessed in human skin explants and human keratinocyte (HaCaT) and hepatocyte cultures. To estimate the amount of the aromatic amine that can reach the general circulation unchanged after passage through the skin the following toxicokinetically relevant parameters were applied: a) Michaelis–Menten kinetics to quantify the epidermal metabolism; b) the estimated keratinocyte cell abundance in the viable epidermis; c) the skin penetration rate; d) the calculated Mean Residence Time in the viable epidermis; e) the viable epidermis thickness and f) the skin permeability coefficient. In a next step, in vitro hepatocyte Km and Vmax values and whole liver mass and cell abundance were used to calculate the scaled intrinsic clearance, which was combined with liver blood flow and fraction of compound unbound in the blood to give hepatic clearance. The systemic exposure in the general circulation (AUC) was extrapolated using internal dose and hepatic clearance, and Cmax was extrapolated (conservative overestimation) using internal dose and volume of distribution, indicating that appropriate toxicokinetic information can be generated based solely on in vitro data. For the hair dye, p-phenylenediamine, these data were found to be in the same order of magnitude as those published for human volunteers. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Toxicology and Applied Pharmacology Elsevier

Extrapolation of systemic bioavailability assessing skin absorption and epidermal and hepatic metabolism of aromatic amine hair dyes in vitro

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Publisher
Elsevier
Copyright
Copyright © 2015 The Authors
ISSN
0041-008x
D.O.I.
10.1016/j.taap.2015.05.016
Publisher site
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Abstract

Approaches to assess the role of absorption, metabolism and excretion of cosmetic ingredients that are based on the integration of different in vitro data are important for their safety assessment, specifically as it offers an opportunity to refine that safety assessment. In order to estimate systemic exposure (AUC) to aromatic amine hair dyes following typical product application conditions, skin penetration and epidermal and systemic metabolic conversion of the parent compound was assessed in human skin explants and human keratinocyte (HaCaT) and hepatocyte cultures. To estimate the amount of the aromatic amine that can reach the general circulation unchanged after passage through the skin the following toxicokinetically relevant parameters were applied: a) Michaelis–Menten kinetics to quantify the epidermal metabolism; b) the estimated keratinocyte cell abundance in the viable epidermis; c) the skin penetration rate; d) the calculated Mean Residence Time in the viable epidermis; e) the viable epidermis thickness and f) the skin permeability coefficient. In a next step, in vitro hepatocyte Km and Vmax values and whole liver mass and cell abundance were used to calculate the scaled intrinsic clearance, which was combined with liver blood flow and fraction of compound unbound in the blood to give hepatic clearance. The systemic exposure in the general circulation (AUC) was extrapolated using internal dose and hepatic clearance, and Cmax was extrapolated (conservative overestimation) using internal dose and volume of distribution, indicating that appropriate toxicokinetic information can be generated based solely on in vitro data. For the hair dye, p-phenylenediamine, these data were found to be in the same order of magnitude as those published for human volunteers.

Journal

Toxicology and Applied PharmacologyElsevier

Published: Sep 1, 2015

References

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  • Skin metabolism of aminophenols: human keratinocytes as a suitable in vitro model to qualitatively predict the dermal transformation of 4-amino-2-hydroxytoluene in vivo
    Goebel, C.; Hewitt, N.J.; Kunze, G.; Wenker, M.; Hein, D.W.; Beck, H.; Skare, J.
  • Xenobiotic metabolism capacities of human skin in comparison with a 3D-epidermis model and keratinocyte-based cell culture as in vitro alternatives for chemical testing: phase II enzymes
    Götz, C.; Pfeiffer, R.; Tigges, J.; Ruwiedel, K.; Hübenthal, U.; Merk, H.F.; Krutmann, J.; Edwards, R.J.; Abel, J.; Pease, C.; Goebel, C.; Hewitt, N.; Fritsche, E.
  • Xenobiotic metabolism capacities of human skin in comparison with a 3D epidermis model and keratinocyte-based cell culture as in vitro alternatives for chemical testing: activating enzymes (Phase I)
    Götz, C.; Pfeiffer, R.; Tigges, J.; Blatz, V.; Jäckh, C.; Freytag, E.M.; Fabian, E.; Landsiedel, R.; Merk, H.F.; Krutmann, J.; Edwards, R.J.; Pease, C.; Goebel, C.; Hewitt, N.; Fritsche, E.

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