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Refinement and enhancement of a database for dermal absorption data

: Schmeinck, Sina; Bitsch, Annette; Genth, H.

Naunyn-Schmiedebergs archives of pharmacology 388 (2015), Supplement 1, pp.S90, Abstract 361
ISSN: 0028-1298
ISSN: 1432-1912
Deutsche Gesellschaft für Experimentelle und Klinische Pharmakologie und Toxikologie (Annual Meeting) <81, 2015, Kiel>
Fraunhofer ITEM ()

Dermal absorption is an important factor in regulatory science regarding the registration of chemicals, agrochemicals and cosmetics. The issue has gained importance since it has been discovered that the skin is not completely impenetrable for chemical substances.[1]
Different ways to assess dermal absorption range from QSAR models to complex in vivo studies including a complete toxicokinetic examination.
The choice of method depends on the question that has to be answered as different systems give different results: absorption as % of applied dose in in vivo studies or permeability coefficient and lag time in infinite dose in vitro studies [1]. Since the OECD has adopted a guideline for assessing dermal penetration in vitro in 2004 the number of in vitro studies is rising continuously.
Depending on the chosen method results may vary in reliability and in acceptance by regulatory authorities.
Based on data shown by Scholz et al. in 2014 [2] about 4200 data sets from the eChemPortal [3] extended with data from the EDETOX database [4] has been analyzed in depth.
In a first approach the references have been reviewed for scientific reliability and categorized in one out of four reliability categories ranging from A as the highest to C as the lowest reliability score. The fourth category D is used for special studies that cannot be compared directly. These are for example repeated dose studies including data on absorption. The data can be used for multiple scenarios: i.e. data for a certain substance or substance class could support read across for registration purposes but also statistic evaluations concerning species or methods used are possible.
The first results taken from the data will be presented showing that up to now 62% of the references are in vitro studies and the number of QSAR studies is rising during the past ten years. Nearly one third of all references are studies using rat skin (30%); about 35% used human skin. Regarding the reliability criteria about one third are marked with the highest category A while only 4% were categorized C for unreliable.
In summary a large dataset with consistent and reliable data from various exposure scenarios can help to provide a reasonable prediction of dermal absorption which can be achieved by our database.
[1]WHO (2006) EHC 235 Dermal absorption.
[2]Scholz et al (2014) Naunyn-Schmiedeberg´s Arch Pharmacol 3 (Suppl 1):S86