Topical tranexamic, a hydrophilic molecule, can't pass the lipid barriers of the stratum
corneum and it's also not retained in adequate amount in the epidermis to enter the
melanocytes, so there's a difficulty in the effective delivery of tranexamic acid into the
melanocytes .
Hyaluronic acid was proved to improve the effective delivery of tranexamic acid through
loosening corneocyte packing and helping TXA entering the melanocytes and minimizing its
epidermal diffusion .