Abstract:

The process leading to the final step of hair shedding is reported to be driven by proteolytic activity and contributes to the detachment of club hair. During late telogen and exogen, increased protease activity may lead to excessive and unwanted hair loss. Materials that can correct proteolytic activity could be beneficial in reducing excessive hair loss. Piroctone olamine was assessed for the protease inhibition efficacy in vitro by deploying a direct fluorescence-based assay for detecting metallo-, serine, acid and sulfhydryl proteases. The assay detects protease activity by the means of a labelled pH-insensitive fluorescent dye where an increase in fluorescence is proportional to protease activity. The assay allows the assessment of materials that may inhibit protease activity of the target enzymes. Since serine proteases have been shown to play a role in the exogen phase of the hair growth cycle, trypsin a known serine protease was used as the target enzyme. Piroctone olamine was found to inhibit trypsin protease activity in a dose-dependent manner. The inhibitory effect was boosted with the addition zinc sulfate. The combination of zinc sulfate with piroctone olamine was formulated into a shampoo base for the evaluation of hair density efficacy in vivo. Male and female participants with hair loss concerns treated their scalp with a shampoo wash （treatment or placebo） 3 times per week for 12 weeks. Hair density was assessed at baseline followed by 4 weekly intervals. The results showed a significant increase in hair density following shampoo treatment versus baseline and versus placebo suggesting the combination of piroctone olamine and zinc sulfate plays a role in retaining hairs and consequently reducing hair fall.

Key words: hair shedding, exogen, hair density, protease, piroctone olamine, zinc sulfate