A recent study found topical tranexamic acid (TA), a plasmin inhibitor, to be effective for treating melasma, with a possible mechanism of action being the suppression of Endothelin 1 (ET-1). Former studies have suggested that TA interferes with the interaction between melanocytes and keratinocytes and may reverse increased vasculature seen in melasma.
The study, published in Clinical and Experimental Dermatology (July 2016), enrolled 23 participants with melasma, who applied a 2% TA formulation to the whole face for 12 weeks. Clinical effects were evaluated using the modified Melasma Area and Severity Index (mMASI) and a chromameter. Skin biopsies were obtained from 10 participants to evaluate pigmentation, vascularity and the expression levels of possible paracrine factors contributing to the effect of TA.
The majority of subjects had mild melasma, with mMASI scores of < 5. The mMASI scores significantly improved in 22 of 23 participants after application. The L* (lightness) values were increased and the a* (red/green) values were decreased in both lesional and perilesional skin. Fontana-Masson staining showed a significant decrease in melanin content in the epidermis. The number of CD31-positive vessels and the expression of the vascular endothelial growth factor both tended to decrease. ET-1 was found to be downregulated with TA.