In Vitro Anti-Dandruff Test

Dandruff is a common scalp problem, mainly caused by Malassezia. The anti-dandruff effect of current shampoos is mainly realized by adding anti-dandruff agents such as stratum corneum exfoliators, cell growth inhibitors or anti-microbial agents. Among the anti-dandruff agents commonly used in cosmetics, salicylic acid is a keratolytic agent, while zinc pyrithione, piroctone ethanolamine salt (OCT), and clomiprazole (CLM) are anti-microbial agents.

Anti-dandruff Test

Cosmetics with anti-dandruff effects should be evaluated by means of cosmetic efficacy claim evaluation tests. For the evaluation of the efficacy of anti-dandruff shampoos, in vitro and human evaluation methods can be used.

• Evaluation of anti-dandruff efficacy by in vitro methods

The most widely used in vitro method is the Malassezia bacterial inhibition test, which is closely related to the formation and development of dandruff, and evaluates the anti-dandruff efficacy of shampoo products according to the size of the inhibitory circle formed by Malassezia furfurfur as an indicator bacterium. Malassezia inhibition test is also widely used in the screening of raw materials with anti-dandruff efficacy, and several papers have documented the use of Malassezia Minimum Inhibitory Concentration (MIC) measurement to screen plant extracts with good anti-dandruff and anti-bacterial effects, and the screened ingredients can be used as a natural alternative to chemical antimicrobial agents to be added to anti-dandruff shampoo products.

• Evaluation of anti-dandruff efficacy by human body method

The human method of evaluating anti-dandruff efficacy mainly adopts double-blind randomized parallel control experiments and "half-head experiments". Double-blind randomized parallel controlled experiments will be randomly divided into two groups of subjects, one of which uses no anti-dandruff ingredients of the shampoo, or each group to use a different efficacy of the ingredients, the same efficacy of the ingredients but different concentrations of the shampoo, and compare the results of the experiments;

The "half-head experiment" is to use two different shampoo products on the left and right sides of the scalp, and evaluate the anti-dandruff effect of the products through self-assessment by the subjects and ratings by the researcher. The following chart shows the results of the self-assessment after using the shampoo products for 4 weeks.

Cautions

It is best to do a uniform treatment on the scalp and hair of the subjects before the start of the various efficacy research trials in order to exclude the interference of different brands of shampoos that the subjects have used in the past. For example, all subjects should be treated with the same non-dandruff shampoo for one week prior to the trial and then clinically scored, and then included in the efficacy trial only after they have met the proposed scoring criteria. Further observation of dandruff flare-ups can be made at the end of the trial period.

Safety Assessment

• Human patch test

A human patch test is used to observe the irritation or sensitization of the test shampoo to human skin.

• Human trial Test

A human trial test is conducted to further verify and observe the safety of the test product in humans. At each follow-up visit, subjects were carefully questioned, examined and recorded any adverse events that occurred during the use of the test product, such as skin and eye irritation, itching of the scalp, change in hair texture, hair loss, etc., including the manifestation of the adverse event, time of occurrence, treatment and regression, and a judgment was made on the relationship between the adverse event and the product used.