Dr Majella Lane
Director, Skin Research Group
UCL School of Pharmacy, London, United Kingdom
Dr Majella Lane will be a Keynote presenter at the 7th Occupational and Environmental Exposure of Skin to Chemicals (OEESC) Conference. She will be speaking on ‘Percutaneous Penetration and Skin Exposure’.
Majella holds a degree in pharmaceutical science and a PhD in membrane transport and her major areas of expertise include delivery of actives to and through the skin, biophysical approaches towards the elucidation of active-skin and formulation-skin interactions, mechanisms of active absorption in skin and topical formulation design and evaluation. Majella acts as a consultant to a number of cosmetic and pharmaceutical companies. She is the Associate Editor of the International Journal of Cosmetic Science and she serves on the editorial board of a number of cosmetic and pharmaceutical science journals. Her research group collaborates worldwide and she also hosts visiting scientists from academia and industry in her laboratory.
Percutaneous penetration with reference to skin exposure
The skin has evolved to keep water in and other xenobiotics or foreign substances out. The outer layer, the stratum corneum, is a unique membrane that is about a sixth of the thickness of a piece of paper. It is composed of dead cells that are filled with keratin and are very dense in nature and it is this thin membrane that is the major barrier to effective percutaneous penetration. Skin penetration of most actives from topical preparations, pharmaceutical or cosmetic formulations does not exceed more than 2-4% of the applied amount. Partly this reflects a lack of focus, historically, on the vehicle or carrier components in which the active is exposed to the skin. Active ingredients vary considerably in water solubility and lipophilicity. The solubility of the active in the vehicle components and vehicle residence time in the skin will be the key determinants of percutaneous penetration of the active. We have recently confirmed this using both in vitro and in vivo studies and specific examples will be given in this presentation. Where the vehicle is volatile in nature there is also the possibility of “stranding” the penetrant in its crystalline form in the outer layers of skin. This will be demonstrated by recent Confocal Raman spectroscopic studies conducted in humans. Nanotechnology continues to revolutionise many aspects of modern life. However, the role of nanotechnology and potential risks to consumers with reference to skin penetration appears to have been overstated. Mathematical models confirm that the rate of diffusion of particles of diameter >1nm is negligible and these will be highlighted. Finally, recent advances in the range and sensitivity of analytical techniques which are already providing better insights into how we may modulate skin exposure will be discussed.
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