Skin permeation and retention of topical bead formulation containing tranexamic acid

The objective of this study is to develop a topical bead formulation of tranexamic acid (TA) which can be used concomitantly with laser treatment. The bead formulation of TA (TAB) was successfully prepared by fluidized bed drying method. Physicochemical properties of the TAB were evaluated in terms of chemical stability of TA and differential scanning calorimetry. TA in the bead was stable up to six months at 25°C and existed as amorphous state. In vitro skin permeation and in vivo skin retention of TA in the beads were significantly higher compared to a commercial product. When the bead was dissolved into distilled water and applied concomitantly with laser treatment, the amount of TA retained in the skin in the in vivo study was inversely proportional to the energy levels of laser treatment, indicating absorption into subcutaneous tissue and drainage to systemic circulation. Therefore, when laser treatment is used concomitantly with TAB, energy level should be very carefully monitored to avoid possible adverse events associated with systemic side effects of TA.