Chalmers Conferences, 9th European Conference on Mathematical and Theoretical Biology

Using mathematical models to exploit the potential of skin in non-invasive drug monitoring
K A Jane White, Begona Delgado-Charro

Last modified: 2014-03-28


The skin represents a large interface for non-invasive sampling techniques which are valuable tools for clinical chemistry, therapeutic drug monitoring and drug abuse screening. Non-invasive sampling decreases infection risks and reduces pain and discomfort; it allows frequent sampling and offers potential for home-monitoring.

The skin provides information on more recent exposures (~ 2 weeks) than hair or nails; is easier to sample than urine, is difficult to adulterate and can be sampled non-invasively by tape-stripping, iontophoresis (the application of a small electric current to establish a solvent flow in the skin) and passively.

Experimental evidence shows that chemicals accumulate into the skin independently of their route of entry into the body. However, there is no systematic knowledge about the extent and rate of this accumulation, its dependence on the physicochemical and pharmacokinetic properties of the chemical, the frequency of exposure and on how to exploit this information.

Furthermore, the skin is a highly structured, heterogeneous organ and pathways for unbound molecules to move across the skin are complex. They consist of an appendageal route (via hair follicles, for example),a paracellular route (travelling around the cells) and a transcellular route (travelling through and between cells). Which route a molecule will take depends again on its physicochemical properties.

In this talk I will discuss two case studies in which mathematical models have been developed and analysed to understand the potential of the skin to provide new insights for drug monitoring. In the first, I will describe how a mathematical model for the formation of a drug reservoir in the skin in patients taking lithium over long periods of time demonstrated the potential for the skin to act as an archive for drug taking behaviour [1]. In the second, I will focus on how a mathematical model was used to explore the pathways for larger molecules, such as the clinical marker iohexol, to cross the skin barrier for monitoring purposes [2].

[1] Paulley, Y., Delgado-Charro, M.B., White, K.A.J., 2010. Comp. Math. Meth. In Medicine 11: 353-368

[2] Djabri, A., 2009. Iontophoresis in paediatric medicine: Non-invasive delivery and monitoring applications. Thesis (Doctor of Philosophy (PhD)). University of Bath.


non-invasive drug monitoring; skin; mathematical models