Clinical Evaluation of Thiamidol-Containing Formulations for the Visual Management of Facial Hyperpigmentation

December 2025 | Volume 24 | Issue 12 | 1195 | Copyright © December 2025


Published online November 30, 2025

Seemal R. Desai MDa,b, Edward (Ted) Lain MDc, Nada Elbuluk MDd, Cheri Frey MDe

aDepartment of Dermatology, The University of Texas Southwestern Medical Center, Dallas, TX
bInnovative Dermatology, Plano, TX
cSanova Dermatology, Austin, TX
dDepartment of Dermatology, Keck School of Medicine, University of Southern California, Los Angeles, CA
eDepartment of Dermatology, Howard University Hospital, Washington DC

Abstract
Background: Cutaneous hyperpigmentation, which includes melasma, post-inflammatory hyperpigmentation, and solar lentigines, significantly impacts patients' quality of life. The overproduction of melanin is mediated by activation of the skin enzyme tyrosinase, leading to excess melanin deposition in the skin. Thiamidol (isobutylamido thiazolyl resorcinol) formulations have been previously shown to be effective in reducing the cutaneous pigmentation associated with this human skin enzyme.
Methods: A randomized study was performed with 90 subjects clinically presenting with facial hyperpigmentation (Thiamidol serum n=43; Thiamidol regimen n=47) as measured by colorimeter and individual typology angle (ITA0) to assess the efficacy of a Thiamidol-based serum (2X daily application; morning/night) or a Thiamidol-based regimen (day lotion with SPF 30 + serum in morning; night cream + serum at night) for 12 weeks with a 6-week regression period.
Results: A significant visible reduction in facial hyperpigmentation, assessed by increases in L* and ITA° values, along with an increase in skin radiance and shine, were observed as early as week 2, with continued improvement through week 12 in both the treatment groups relative to baseline. At week 12, changes in radiance and shine were trending toward enhancement in the regimen group compared with the serum group.
Discussion: This study demonstrates the clinical effectiveness of Thiamidol-containing formulations in the visible improvement of facial hyperpigmentation and in overall skin radiance and shine.
Conclusion: These data support the use of Thiamidol-containing formulations as part of the overall management strategy for individuals affected by facial hyperpigmentation.

 

INTRODUCTION

Pigmentary disorders, including melasma, post-inflammatory hyperpigmentation (PIH), solar lentigines, axillary hyperpigmentation, periorbital hyperpigmentation, and vitiligo, are some of the most commonly reported dermatological skin disorders, which significantly impact patients' quality of life.1,2 In a recent survey of 48,000 individuals from 34 countries covering all continents, 50% of the subjects (average age 44 years) reported having at least one pigmentary disorder, with more women (59%) affected.1 Amongst these disorders, hyperpigmentation-associated skin disorders, primarily melasma, PIH, and solar lentigo, accounted for the majority of the self-reported conditions.1 Furthermore, in individuals with skin of color (SOC), particularly those with African, Asian, or Hispanic heritage, the incidence of reported PIH far exceeded that of the general population (15% vs ~1%).1 Hyperpigmentation is mediated by the overstimulation of the melanin production pathways in melanocytes, resulting in the deposition of excess melanin in the skin.3,4 The key rate-limiting step in these complex pathways centers on the conversion of Tyrosine to L-Dopa, via the catalyzing enzyme tyrosinase, with eventual generation of the melanin end products eumelanin and pheomelanin.5

Recently, isobutylamido thiazolyl resorcinol (Thiamidol) has been identified from a library of 50,000 compounds as the most effective inhibitor of human tyrosinase with activity (half-maximal inhibition concentration, IC50 = 1.1 mmol/L). This far exceeds that of common anti-pigmentation ingredients, including hydroquinone and kojic acid,6 making it a suitable ingredient for inclusion in over-the-counter (OTC) anti-pigmentation products.
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