Docosanol is an over-the-counter topical agent that has proved to be one of the most effective
therapies for treating
herpes simplex labialis. However, the mechanism by which
docosanol suppresses lesion formation remains poorly understood. To elucidate its mechanism of action, we investigated the uptake of
docosanol in living cells using coherent anti-Stokes Raman scattering microscopy. Based on direct visualization of the deuterated
docosanol, we observed highly concentrated
docosanol inside living cells 24 h after
drug treatment. In addition, different spatial patterns of
drug accumulation were observed in different cell lines. In keratinocytes, which are the targeted cells of
docosanol, the
drug molecules appeared to be docking at the periphery of the cell membrane. In contrast, the
drug molecules in fibroblasts appeared to accumulate in densely packed punctate regions throughout the cytoplasm. These results suggest that this molecular imaging approach is suitable for the longitudinal tracking of
drug molecules in living cells to identify cell-specific trafficking and may also have implications for elucidating the mechanism by which
docosanol suppresses lesion formation.