Cortisol extraction through human skin by reverse iontophoresis

Area of Science:

• Biomedical Engineering
• Pharmacokinetics
• Dermatology

Background:

• Continuous cortisol monitoring is crucial for diagnosing cortisol-related diseases and managing stress.
• Current methods for skin cortisol detection are limited, hindering real-time monitoring.
• Reverse iontophoresis offers a potential solution for non-invasive transdermal analyte extraction.

Purpose of the Study:

• To investigate the efficacy of reverse iontophoresis for extracting cortisol through human skin in vitro.
• To determine the optimal direct current (DC) regimens for maximizing cortisol transport.
• To explore the potential for developing wearable devices for continuous cortisol monitoring.

Main Methods:

• Cortisol extraction was studied in vitro using excised human skin in side-by-side diffusion cells.
• Radiolabeled 3H-cortisol was used as a probe to quantify transdermal transport.
• Four direct current regimens (0, 28, 56, 113 μAcm⁻²) were applied with the anode in the donor chamber.
• Cumulative cortisol concentrations were measured in the receiver chamber.

Main Results:

• Direct current regimens of 56 and 113 μAcm⁻² significantly enhanced 3H-cortisol transport across the skin.
• A direct correlation was observed between current density and transcutaneous cortisol transport.
• The detection threshold for electroosmotic versus passive cortisol diffusion was identified between 28 and 56 μAcm⁻².
• The study examined the response of lipophilic analytes to reverse iontophoresis.

Conclusions:

• Reverse iontophoresis effectively extracts cortisol through human skin, with higher current densities yielding greater transport.
• The findings establish a threshold for electroosmotic transport, crucial for optimizing iontophoresis protocols.
• This research supports the development of wearable devices for continuous, non-invasive cortisol monitoring, aiding in disease diagnosis and stress assessment.