Kojic acid, a pyrone derivative obtained from the fermentation process of Japanese liquor, was found to be an excellent whitening agent in 1982. At that time, it was applied at 1% concentration in cream to melasma, secondary pigmentation and other types of superficial melanosis for several months. In this study, Kojic acid at 0.5% in milky lotion, 0.5% lotion, 0.5% essence and 1% cream with adding liquiritin at 0.03% were clinically evaluated by a simple application twice a day on various pigmentary disorders mainly on the face. The rates of effectiveness were 86.9%, 84.2%, 78.5% and 86.5%, respectively. These results were as good as the previous findings using 1% Kojic acid cream. However, the addition of liquiritin seems to have speeded up the effect of Kojic acid. Therefore, Iiquid preparations are sometimes more suitable than cream for application over wide areas of pigmentary disorders.
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