Thiamidol containing treatment regimens in facial hyperpigmentation: An international multi‐centre approach consisting of a double‐blind, controlled, split‐face study and of an open‐label, real‐world study

Objective Tyrosinase is the rate‐limiting enzyme in melanogenesis. Thiamidol is the most potent inhibitor of human tyrosinase out of 50 000 tested compounds. In clinical studies, it was shown to improve facial hyperpigmentation, post‐inflammatory hyperpigmentation and age spots significantly. To identify the optimal number of daily Thiamidol applications, we conducted a split‐face study comparing the efficacy and tolerability of four‐times with two‐times daily application. Subsequently, we evaluated the efficacy and tolerability of a typical face care regimen containing Thiamidol in a real‐world study. Methods The split‐face study was double‐blind, randomized, controlled, including two Thiamidol containing products (serum and day care SPF 30). The serum was applied twice daily on one half of the face and the day care SPF30 twice‐daily on the whole face. The real‐world study was open‐label, observational, including three Thiamidol containing products (day care SPF 30 in the morning, serum and night care in the evening). In both studies, subjects with mild‐to‐moderate facial hyperpigmentation applied the products over 12 weeks. Assessments included clinical and subjective grading of hyperpigmentation, skin condition, hemi‐/modified MASI, chromameter and clinical photography. Results In the split‐face study (n = 34), hyperpigmentation, skin roughness and hMASI improved all significantly (P