Flux of a Nickel(II) Salt versus a Nickel(II) Soap across Human Skin in vitro

Abstract

Background: Contrary to in vitro data on skin diffusivity of nickel salts indicating slow rates of diffusion, contact allergy to nickel among the general population is frequent, indicating facile skin penetration. Objective: To demonstrate that the preferred diffusion of a lipophilic oxidation product of nickel formed in contact with the skin follows the multilamellar lipid region which envelops the corneocytes. Method: Diffusion of nickel chloride was compared with that of the lipophilic nickel soap, the dioctanoate. Results: The dioctanoate soap showed a significantly lower rate of diffusion (K_p = 1.4 × 10^–3 ± 5.7 × 10^–4 cm/h) than the chloride salt (K_p = 9.8 × 10^–3 ± 4.8 × 10^–4 cm/h), with a relatively high level of nickel retained in the tissue. Conclusions: (a) The molecular volume of the nickel dioctanoate overrides the effect of compound polarity; (b) the rates of diffusion measured through dermatomed skin are higher than those heretofore measured through full-thickness skin, epidermal tissue or stratum corneum; (c) both the nickel salt and soap appear to diffuse primarily via appendages; (d) the cause for the pronounced immune response to nickel in contact with the skin appears to lie in amounts retained in the viable skin strata; (e) skin from a young donor appears more permeable to nickel compounds than skin from an older source stemming from the same anatomical site.

In VitroPermeation of Metals through Human Skin: A Review and Recommendations

“…Moody et al investigated in vitro dermal permeation of nickel as Ni-63 in soil and without soil by using human breast skin (refer to mercury for more detail) and found a high total absorption as a result of a high percentage of nickel retained inside the skin (depot/reservoir). Comparison of their results to those of Hostýnek indicated a lower percentage of permeation (1.8% vs. 35.7%) and a higher percentage of retention in the skin (20.9% vs. 0.02%). The authors suggested the appendageal shunt route as a contributing factor to the difference in results.…”

“…The authors suggested that the higher permeability of NiCl 2 may be due to higher cutaneous bioavailability of the salt . Hostýnek , also reported higher permeability coefficients for NiCl 2 when compared with that of other nickel compounds. In contrast, Tanojo et al reported a higher percentage of permeation for NiSO 4 when compared with that of NiCl 2 when using the SC only.…”

“…Hostýnek reported higher permeation of NiCl 2 through dermatomed skin when compared with that of a Ni­(II) soap and higher permeability of both nickel compounds through adolescent skin (14 years) than through elderly skin (67 years).…”

“…The in vitro permeation of chromium, as well as that of nickel and cobalt, was also investigated by Larese et al 20 Chromium 10,15,25,40 number of donors per study 1, 2, 3, 4, 14 13,19,25,31,41 gender of skin donors included per study male and female, female only, male only [18][19][20]30 age of skin donors included per study powder did not permeate the skin, and the study concluded that metallic chromium was not oxidized in synthetic sweat with a pH of 6.5; therefore, no permeation of chromium occurred under normal physiological conditions. 20 In a follow-up study, Larese Filon et al 28 investigated the permeation of chromium powder through skin at a pH of 4.5 and found chromium permeation through the skin.…”

Nickel penetration into stratum corneum in FLG null carriers—A human experimental study

“…10 In vitro methods using diffusion cells for assessment of percutaneous absorption, measure penetration of chemicals into the skin and their permeation into a receptor fluid. This methodology has been used with ex vivo human or piglet skin to study permeation of aqueous nickel chloride, nickel sulphate, [12][13][14] and pure nickel dissolved in HNO 3 . 15 Collectively, the studies show that nickel in different forms may penetrate into skin, even after short duration of exposure.…”