Dandruff or seborrhoeic dermatitis caused by Malassezia yeasts is treatable using topical gels with anti-fungal properties. Rinse-off shampoos are common in use among the affected people. These solutions are effective only if they target the yeast’s distribution on the scalp. This study looks at the therapeutic effects of applying shampoos on the scalp’s follicular infundibula (hair cavities). The study also aims to determine if it is possible to deliver ZPT to the scalp’s highly restricted structures.

Observations prove that the yeasts reside in follicular cavities of the scalp. Commercial shampoos with zinc pyrithione (ZPT) as an active ingredient are the subjects in the study. In one method, the researchers analyzed the infundibular spaces using image analysis and chemical quantification. In two other methods were hair plucks and infundibular biopsies. The subsurface portion and extracted ZPT underwent chemical quantification.

 The outcomes were positive as the detection of infundibular ZPT was successful. Its quantity also correlated to the decrease in yeast population. High levels of ZPT in commercial shampoos reached the infundibular spaces, disproportionately. Only the active ingredient in optimal sizes had the potential to treat the affected spaces. 

Therapeutic products deliver anti-fungal material to the infundibulum and scalp surface. However, only certain therapeutic shampoos with optimal ZPT size were efficient in spatial delivery.

Ref: https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2133.2011.10573.x