Visualization of Epidermal Reservoir Formation from Topical Diclofenac Gels by Raman Spectroscopy.

This work investigated whether topical pain relief diclofenac gels can form a diclofenac reservoir in the epidermal and dermal layers of human skin. Excised human skin samples were treated with three topical diclofenac gels ex vivo and examined using Raman microscopy of transversally microtomed sections. The relative diclofenac concentration in the skin layers was calculated as the ratio of the integrated areas of bands characteristic of diclofenac (~445 cm A heterogenous spatial distribution of diclofenac was clearly visible in both the epidermis and the dermis in all samples, with a markedly higher diclofenac relative content and number of pixels above the detection limit in the epidermis compared to the dermis. The Raman images evidenced that the studied topical gels deliver diclofenac through the stratum corneum skin barrier and form a drug depot localized in the epidermis. The data are in line with earlier clinical findings that this depot acts like a true reservoir and enables sustained drug release.

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© 2020 Zhang et al.

Déclaration de conflit d'intérêts

Mila Boncheva Bettex is an employee of GSK Consumer Healthcare S.A. Skin samples were contracted to Charles River Laboratories in studies directed by Leanne Page and Susan Whitson. The spectroscopic work was contracted to Rutgers University and performed by Qihong Zhang, Carol R. Flach, and Richard Mendelsohn. This work was funded by GSK Consumer Healthcare S.A. The authors report no other conflicts of interest in this work.