title: The impact of skin viability on drug metabolism and permeation -- BSA toxicity on primary keratinocytes.
abstract: For testing cutaneous absorption of drugs, ingredients of cosmetics and also for risk assessment of industrial compounds predictable in vitro test protocols are under investigation using excised skin or reconstructed human epidermis. Since the metabolizing enzymes expressed by viable skin can influence the absorption behaviour of substances by changing their structure and thereby their physicochemical characteristics, the metabolic capacity should be considered in the design of the test protocols of compounds susceptible to metabolism. Then data, generated using viable reconstructed epidermis may reflect the in vivo situation. Interestingly, bovine serum albumin (BSA) commonly used in receptor media in permeation studies to facilitate solubility of highly lipophilic substances strongly inhibited the metabolism of topically applied prednicarbate in reconstructed epidermis. Here, we show that 5% BSA is toxic to reconstructed epidermis and keratinocytes which was consistent with the earlier findings. While media toxicity (deficiency media) was at least partly the cause of both apoptotic and necrotic processes in keratinocytes, BSA only slightly increased the rate of necrotic cells. Moreover, caspase inhibitors did not reduce BSA toxicity. Yet, the results show that BSA toxicity on keratinocytes has to be carefully considered if this protein is used in permeation studies with reconstructed epidermis.
authors.affiliation: Institut für Pharmazie (Pharmakologie und Toxikologie), Freie Universität Berlin, Königin-Luise-Str. 2+4, D-14195 Berlin, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Haberland
authors.forename: S
authors.initials: S
authors.lastname: Schreiber
authors.forename: C Santos
authors.initials: CS
authors.lastname: Maia
authors.forename: M K
authors.initials: MK
authors.lastname: Rübbelke
authors.forename: M
authors.initials: M
authors.lastname: Schaller
authors.forename: H C
authors.initials: HC
authors.lastname: Korting
authors.forename: B
authors.initials: B
authors.lastname: Kleuser
authors.forename: I
authors.initials: I
authors.lastname: Schimke
authors.forename: M
authors.initials: M
authors.lastname: Schäfer-Korting
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D053181:Caspase 8; D061945:Caspase Inhibitors; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D003470:Culture Media; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000078404:Epidermal Cells; D004817:Epidermis / Q000187:drug effects / Q000378:metabolism; D005456:Fluorescent Dyes; D005938:Glucocorticoids / Q000378:metabolism; D006801:Humans; D007211:Indoles; D015603:Keratinocytes / Q000187:drug effects*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D010539:Permeability; D004364:Pharmaceutical Preparations / Q000378:metabolism*; D011419:Propidium / Q000633:toxicity; D012710:Serum Albumin, Bovine / Q000633:toxicity*; D012867:Skin / Q000378:metabolism*; D012869:Skin Absorption
chemical_list: D017304:Annexin A5; D061945:Caspase Inhibitors; D003470:Culture Media; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D005938:Glucocorticoids; D007211:Indoles; D004364:Pharmaceutical Preparations; D012710:Serum Albumin, Bovine; D011419:Propidium; C007293:DAPI; D007770:L-Lactate Dehydrogenase; C505530:CASP8 protein, human; D053181:Caspase 8