Recently, isobutylamido-thiazolyl-resorcinol (thiamidol) was described as a very potent inhibitor of human tyrosinase. 

The aim of a new study published in the International Journal of Cosmetic Science investigated the potential of this compound to prevent post-inflammatory hyperpigmentation (PIH) induced by epidermal wounding (suction blister) and related to acne.

In this experiment, suction blister-induced PIH was treated with a formulation containing thiamidol or a vehicle for three months and the changes in hyperpigmentation were monitored by spectroscopic measurements. The effect of skin care formulations containing thiamidol on acne-related PIH was investigated in two studies, a vehicle-controlled, double-blinded, randomized clinical study and a clinical observational study. 

The results revealed that after 2 weeks of treatment, suction blister sites treated with thiamidol were significantly lighter than control sites and improved throughout the treatment period. Meanwhile, participants reported that thiamidol significantly improved the visibility of acne-induced hyperpigmentation compared to the vehicle treatment. Furthermore, a skin care regimen with thiamidol significantly improved acne-related PIH over 12 weeks—as shown by Mexameter measurements, expert grading, self-grading and clinical photography.

In inference, it was stated that thiamidol represents a safe and effective ingredient for cosmetic products against post-inflammatory hyperpigmentation.

Source: International Journal of Cosmetic Science. 2021 Feb 8. doi: 10.1111/ics.12694.