Does magnesium permeate the skin? An ex vivo investigation of magnesium ion delivery through intact and barrier-disrupted skin.

The potential for cutaneous magnesium delivery remains uncertain despite widespread use of topical formulations. This study aimed to directly evaluate magnesium ion permeation from a saturated aqueous magnesium sulfate monohydrate solution across porcine skin using an ex vivo Franz diffusion cell model. Permeated magnesium was quantified by inductively coupled plasma mass spectrometry in both intact and tape-stripped porcine skin, the latter representing impaired barrier conditions. Minimal magnesium permeation was observed across intact skin, with no significant difference between magnesium-treated and control samples, where magnesium permeation after 24 h was found to be 8.3 ± 3.4 µg cm-2 (magnesium-treated) as compared to 3.9 ± 0.8 µg cm-2 (control). In contrast, tape stripping resulted in a marked increase in magnesium permeation to approximately 13.0 ± 5.3 mg cm-2, representing an increase of several orders of magnitude. Substantial inter-individual variability was observed in barrier-impaired skin. The findings of this study demonstrate that magnesium permeation is strongly limited by the stratum corneum and that transdermal magnesium delivery from simple aqueous solutions is unlikely under normal physiological conditions. However, significantly enhanced permeation may occur in compromised skin. Overall, the study highlights the critical role of skin barrier integrity in regulating magnesium permeation and provides insight into the limitations of topical magnesium application.