The measurement of iron clearance from the skin

Transdermal Delivery of Iron Using Soluble Microneedles: Dermal Kinetics and Safety

Currently, the iron compounds are administered via oral and parenteral routes in patients of all ages, to treat iron deficiency. Despite continued efforts to supplement iron via these conventional routes, iron deficiency still remains the most prevalent nutritional disorder all over the world. Transdermal replenishment of iron is a novel, potential approach of iron replenishment. Ferric pyrophosphate (FPP) was found to be a suitable source of iron for transdermal replenishment. The safety of FPP was assessed in this project by challenging the dermal fibroblast cells with high concentration of FPP. The cell viability assay and reactive oxygen species assay were performed. The soluble microneedle array was developed, incorporated with FPP and the kinetics of free iron in the skin; extracellular fluid following dermal administration of microneedle array was investigated in hairless rats. From the cell based assays, FPP was selected as one of the potential iron sources for transdermal delivery. The microneedles were found to dissolve in the skin fluid within 3 hours of administration. The FPP concentration in the dermal extracellular fluid declined after complete dissolution of the microneedle array. Overall, the studies demonstrated the safety of FPP for dermal delivery and the feasibility of soluble microneedle approach for transdermal iron replenishment therapy.

Metals and the skin

Certain metals, and many metal-based compounds, are inherently toxic, and their presence in occupational and environmental settings raises appropriate questions concerning human exposure. Contact of these materials with the skin represents an important route of exposure, which is not well characterized. The purpose of this review, therefore, is to assemble the available, useful information pertinent to risk assessment following dermal contact. Specifically, we summarize here: (1) data relevant to the qualitative and (where possible) quantitative evaluation of metal compound permeation through the skin; (2) the role of each metal in metabolism, particularly with respect to the skin, and the potentially toxic effects that may result from dermal contact; and (3) the immunological characteristics (including allergenicity) of the metals and their derivatives. In total, information on 31 metals has been reviewed. It is clear that many diverse factors determine the ability of metal-based species to permeate biological membranes, not all of which have been fully defined. Therefore, considerably more experimentation, targeted at the development of high-quality transport data, will be required before the specification of practically useful structure-activity relationships are possible.