title: Validation of freeze-drying to visualize percutaneous 3H-estradiol transport: the influence of skin hydration on the efficacy of the method.
abstract: A study was made of the validity of freeze-drying to visualize the distribution of 3H-estradiol in human stratum corneum after topical application of a dry dose, a patch or a buffer solution. Each of these donor formulations was applied to human dermatomed skin for 24 h using Franz permeation cells. Subsequently, small pieces of skin were subjected to cryofixation, freeze-drying, osmium tetroxide vapor fixation, Spurr resin embedding and electron microscopic autoradiography. Stratum corneum from dry dose and patch application experiments was well preserved by freeze-drying, allowing an accurate localization of 3H-estradiol. In contrast, stratum corneum from buffer solution experiments suffered from cryofixation artifacts due to excessive hydration of the skin. The corresponding autoradiographs showed strong redistribution of 3H-estradiol. Thus, the visualization method under investigation has its limitations regarding the hydration level of the skin.
authors.affiliation: Astra Pain Control AB, Södertälje, Sweden. jan.neelissen@pain.se.astra.com
authors.forename: J A
authors.initials: JA
authors.lastname: Neelissen
authors.forename: C
authors.initials: C
authors.lastname: Arth
authors.forename: A H
authors.initials: AH
authors.lastname: Schrijvers
authors.forename: H E
authors.initials: HE
authors.lastname: Junginger
authors.forename: H E
authors.initials: HE
authors.lastname: Boddé
mesh_terms: D016477:Artifacts; D001345:Autoradiography; D001692:Biological Transport; D002021:Buffers; D004958:Estradiol / Q000493:pharmacokinetics*; D005612:Freeze Drying; D006801:Humans; D015203:Reproducibility of Results; D012867:Skin / Q000378:metabolism* / Q000648:ultrastructure; D013048:Specimen Handling / Q000379:methods*; D014316:Tritium; D014867:Water / Q000378:metabolism*
chemical_list: D002021:Buffers; D014867:Water; D014316:Tritium; D004958:Estradiol