Investigation of Transfollicular Caffeine Penetration Using Microdialysis on Ex Vivo Porcine Ear Skin

In this study using ex vivo porcine ear skin, researchers found that standard nail varnish applied gently creates effective follicular closures, preventing penetration of certain substances like fluorescein sodium salt and caffeine into hair follicles, whereas solvent-free varnish and rapid application techniques were less effective.

This study found that nanoemulsion formulations with oleic acid or eucalyptol significantly enhanced the delivery and retention of caffeine through hair follicles and surrounding skin regions.

This study presented a new two-dimensional model that successfully predicts transdermal permeation of caffeine, highlighting the significant role of the follicular pathway in increasing systemic bioavailability.

This study found that the contribution of the hair follicle pathway to skin permeation of chemicals can be predicted using lipophilicity, with hydrophilic chemicals showing greater permeation reduction from hair follicle plugging than lipophilic ones.

This study highlights the significance of the hf pathway for the skin permeation of ionized and hydrophilic high molecular compounds, and the usefulness of hf-plugging in evaluating their skin permeability.

This review summarizes drug delivery strategies to hair follicles, highlighting physicochemical factors affecting penetration and the use of stimuli-responsive particulate carriers, but reports no new clinical findings.

This study found that caffeine and flufenamic acid penetrated porcine skin more effectively through hair follicles, while the importance of the follicular pathway varied for other substances tested.

The human hair follicle can store topical compounds and be targeted for drug delivery with minimal side effects.

This study found that hair follicles contribute significantly to caffeine absorption shortly after topical application, with a faster absorption rate compared to the stratum corneum.

The study reported that combining the Follicular Closing Technique with the Franz diffusion cell is a valuable method for investigating follicular caffeine penetration in vitro, though kinetics differ from in vivo results.

This study demonstrated that hair follicles significantly expedite the absorption of caffeine through the skin compared to interfollicular pathways.

This review examines the role of hair follicles and sebaceous glands in percutaneous drug delivery but does not report new clinical results; it calls for further exploration of follicle-targeting therapies.

This study found that hair follicle characteristics vary significantly across different body sites, with the forehead and calf showing the highest potential follicular reservoirs, challenging previous assumptions about skin appendage distribution.