MATERIAL AND METHODS Model characterization• 2D-cell cultureHepG2 cells (ATCC) are seeded in a 96-well white plate (20,000 cells/well) 24h before treatment in 200µL of phe-nol red-free defined media.

CHARACTERIZATION OF THE MODEL

EFFECT OF LONG TERM TREATMENT

Endpoints

• Pictures of spheroids recorded daily before treatment with a microscope (Zeiss)

• Spheroid size monitoring: diameter were measured using ImageJ software.

• Cell viability, Celltiter-Glo 3D (Promega, France)

• Human Albumin quantification in supernatants (ABCAM).

Arno Wahler1, Bernadette David1, Chantal Jouy2, Marie-Lise Chiron2, Clémence Cossec2, Bruno Biatry3, Sébastien Gregoire4, Odile Aubrun1, Guillaume Cassin3

1L’Oréal Research & Innovation, Transversal Expertise Physical-Chemistry, 2Applied Research Anti-Aging, 3Transversal Expertise Sciences of Formulation, 4Advanced Research ADME Pole

 PHYSICAL-CHEMICAL APPROACH FOR EXPLORING THE SKIN AVAILABILITY

OF COSMETIC INGREDIENTS

Crystallization of caffeine & Oil release

Deposits microscopy with 200 µm thickness deposits (average film thickness in In-vitro test) at 32°C-50% RH.

In less than 1hour, equilibration is reachedFor both emulsions, main component of deposits is oil

In watery phase, fast caffeine crystallization

In oily phase, No HC-1 crystallization

Upon drying, coalescence occurs, with residual droplets that remained stable

Along diffusion time, Caffeine crystallizes in watery phase which limits its delivery

Additional effect of oil [3]

Penetration of oil

Micro tomography experiments : penetration of the formulae in the Strat-M membrane – Qualitative ranking

X-ray micro tomography (NOVITOM)

of the Strat-M membrane before and

after oil phase application

Emulsions and oily phase

penetrates in the oily layer

of the membrane

OBJECTIVES & APPROACH

IN VITRO AND EX VIVO RESULTS

EMULSIONS’ PERFORMANCES – PRELIMINARY DISCUSSIONS

RÉFÉRENCES

[1] S. Grégoire C. Ribaud F. Benech J.R. Meunier A. Garrigues-Mazert and R.H. Guy, Prediction of chemical absorption into and through the skin from cosmetic and dermatological formulations, British Journal of Dermatology, 2009, 160, 80–91 (DOI 10.1111/j.1365-2133.2008.08866.x)

[2] Sebastian Björklund, Jenny Marie Andersson, Quoc Dat Pham, Agnieszka Nowacka, Daniel Topgaard and Emma Sparr, Stratum corneum molecular mobility in the presence of natural moisturizers, Soft Matter, 2014, 10, 4535–4546

[3] Shweta A. Raina, Geoff G. Z. Zhang, David E. Alonzo, Jianwei W, Donghua Zhu, Nathaniel D. Catron, Yi Gao, Lynne S. Taylor, Impact of Solubilizing Additives on Supersaturation and Membrane Transport of Drugs, Pharm Res, 2015, 32, 3350–3364 (DOI 10.1007/s11095-015-1712-4)

[4] Hiroaki Todo, Takeshi Oshizaka, Wesam R. Kadhum & Kenji Sugibayashi, Mathematical Model to Predict Skin Concentration after Topical Application of Drugs, Pharmaceutics 2013, 5, 634-651

AWAHLER@RD.LOREAL.COM

HC-1 is propably in membrane,’s tank just as in

Stratum corneum

Further characterizations & modeling [4] confirmed

theses hypothesis

The Strat-M membrane (Millipore)

Hansen Solubility Parameters of the Stratum corneum

Surface energy 37mN.m-1 Contact surface 1,77cm2

Total Thickness 300µm – Oily layer thickness 85 µm

To mimic the behavior of Skin is not the objectiveIt is to detect performances and to rank

Per layer content1 value at 16h

EvaluationBottle-neck

Receptor contentDiffusion profile

Relevancy ?

Which formula leads to the best delivery ?

Comparison of solutions vs emulsions

Caffeine results (Medium hydrophilic)

HC-1 results (Lipophilic)

Franz’s cell & Strat-MBetter understood and used

Identification of new formulation rules

Applications on going for skin care products

Active structure - Distribution profile

In vitro – Ex vivo comparison• High variability in ex-vivo results didn’t allow to discriminate the 3 vehicles• Strat-M test allow a better discrimination of the formulae• Higher rate of diffusion for caffeine than for HC-1 in both tests• The kinetic between the two protocols seems very different.

Emulsions more efficient for both actives compared to solutions• For caffeine, inverse emulsion appears better on Strat-M, • For HC-1, both emulsions have similar performances, on both tests.• Diffusion rates affected by the organization and the thermodynamic state of

the actives within

Distribution in the skin layers • Skin partitioning in agreement with the actives’ structure and properties [1]• Caffeine mostly present in the dermis and receptor fluid• HC-1 equally partitioned between the Stratum corneum and the living layers.

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