The efficacy of tranexamic acid in the treatment of melasma

Melasma is a common skin pigmentary disorder 1. Genetic predisposition, ultraviolet (UV) exposure, and hormonal factors play roles in its pathogenesis. Tranexamic acid (TA) is a synthetic derivative of the lysine, which prevents abnormal fibrinolysis. It acts through inhibiting plasminogen activator (PA) from converting plasminogen to plasmin. For the first time, in 1979, Nijo Sadako accidentally found the efficacy of this compound in treating melasma. The plasminogen exists in the human epidermal basal cells and keratinocytes. Induction of the keratinocyte-PA system by UV exposure results in the melanogenesis process. Furthermore, oral contraceptive pills and pregnancy activate this process through increasing the serum PA. In this article, Tse and Hui reviewed the efficacy of TA in the treatment of melasma. Studies have revealed that oral TA alone or in combination with oral supplements, such as vitamins C and E, is effective in treating melasma. In one study, oral TA was successfully used as adjuvant in combination with intense pulse light or neodymium-doped yttrium aluminium garnet (Nd:Yag) laser for managing this pigmentary disorder. Studies about the effectiveness of topical TA in treating melasma have shown controversial results. A study showed that the intradermal injections of TA were effective in decreasing severity of this skin disorder. Since 2007, the intravenous TA has been prescribed for skin whitening. In a study on neonatal foreskin-cultured melanocytes, it was confirmed that TA acts by preventing the multiplication of melanocyte and by decreasing tyrosinase activity, tyrosinase-related protein, and melanin content in the melanocytes. In another study on guinea pigs, the efficacy of intradermal TA in melanin content of the melanocytes after UV exposure was shown. In the end, the authors concluded that TA is effective in treating melasma. Nausea, diarrhea, orthostatic reactions, and, in rare cases, skin reaction, acute renal cortical necrosis, and disturbances in color vision have been reported in its side effect profile. Commentary: TA can be used safely as adjuvant in the treatment of melasma.