Tranexamic Acid also known as (TXA) helps prevent the formation of new visible hyperpigmentation by slowing the production of melanin by inhibiting a pathway know as the plasmin pathway.
When the skin is injured through cuts, chemical burns, SLS-based surfactant damage, tape-stripping, or UV exposure, your skin cells produce a compound called Plasminogen Activator (PA) which is responsible for activating Plasminogen into Plasmin. Plasminogen is the precursor for Plasmin and it exists in human epidermal basal cells. Plasmin, a serine protease, is responsible for initiating wound healing by activating keratinocyte proliferation (exfoliation) and migration. It also starts several processes that lead to inflammation, melanogenesis, and other processes.
Plasmin’s production in the skin is one of the triggers of inflammation because it activates several signaling pathways that lead to the production of cytokines (inflammatory messengers), ROS, and other mediators. Aside from their inflammatory role, they also are potent melanogenic factors that tell your melanocytes to overproduce melanin. Plasmin also enhances the release of an alpha-melanocyte-stimulating hormone (α‑MSH), which tells your melanocytes to activate and produce more melanin. In comes melasma, hyperpigmentation etc.
TXA binds and suppresses sc-uPA binding to cell membrane receptors, thereby preventing Plasminogen’s activation to Plasmin. TXA’s anti-plasmin activity makes it a great candidate for inhibiting melanogenesis by inhibiting keratinocyte-melanocyte interaction through the inhibition of the plasminogen-plasmin system. It inhibits tyrosinaseactivity. TXA can mediate a decrease in melanin synthesis by alleviating the production of tyrosinase and TRP1/2, along with lowered MITF protein levels.
In short : Unlike our other favorite skin care acids, like the salicylic or glycolic varieties, tranexamic acid is not an exfoliant. It’s derived from the essential amino acid lysine, which slows melanin synthesis.
Essentially, it works by blocking the interaction between the melanocytes, which are the cells that make melanin (responsible for skin pigment) and the keratinocytes, the surface skin cells. As a result, it can help lighten areas of discoloration and melasma. One 2019 study found that a 5 percent tranexamic acid solution was as effective at treating the latter as a hydroquinone cream, the"gold standard" treatment for the condition.