Effective Reduction of Acne-induced Post-inflammatory Hyperpigmentation with the Human Tyrosinase Inhibitor Thiamidol (isobutylamido thiazolyl resorcinol)

Objective: Post-inflammatory hyperpigmentation (PIH) is a major cosmetic concern especially in individuals with darker skin complexion. Unfortunately, treatment with anti-inflammatory ingredients alone does not prevent the development of hyperpigmented spots. Recently, Thiamidol (isobutylamido thiazolyl resorcinol) was described as a very potent inhibitor of human tyrosinase. The objective of this research was to investigate the potential of Thiamidol-based formulations to prevent PIH induced by acne-induced epidermal wounding. Methods: 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. Both studies had a duration of 3 months and included assessments of clinical photography, clinical grading and melanin index measurements. Results: Subjects’ self-grading demonstrated that Thiamidol significantly improved the visibility of acne-induced hyperpigmentation compared to the vehicle treatment. A skin care regimen with Thiamidol significantly improved acne-related PIH over 12 weeks shown by Mexameter measurements, expert grading, self-grading and clinical photography. Conclusion: Thiamidol represents a safe and effective ingredient for cosmetic products against post-inflammatory hyperpigmentation.