Effective Tyrosinase Inhibition by Thiamidol Results in Significant Improvement of Mild to Moderate Melasma

Melasma is a pigmentary disorder characterized by hyperpigmented patchy skin in sun-exposed areas, especially the face. Treatment of melasma can be challenging because long-term therapy is required, reoccurrence is common, and existing therapies are insufficient and unsatisfactory. To investigate new treatment options, we performed an exploratory double-blinded, randomized split-face study to assess the efficacy of the tyrosinase inhibitor Thiamidol compared to hydroquinone in women with mild to moderate melasma. After 12 weeks, modified Melasma Area and Severity Index scores significantly improved on both the Thiamidol-treated and the hydroquinone-treated sides of the face. Additionally, Thiamidol treatment improved modified Melasma Area and Severity Index scores significantly better than hydroquinone, and more subjects improved following treatment with Thiamidol (79%) compared with hydroquinone (61%). During treatment, no subjects displayed worsening of modified Melasma Area and Severity Index scores on the Thiamidol-treated side, while approximately 10% of the subjects showed a worsening of modified Melasma Area and Severity Index scores on the hydroquinone-treated side. All subjects routinely used sunscreens and consistent results were obtained in low and in high UV ambient conditions. Subjects rated the efficacy of the Thiamidol formulation significantly better with regard to overall decreased intensity of dark spots and their overall appearance throughout the study. Thiamidol was well-tolerated and well-perceived and represents an effective agent to reduce hyperpigmentation.