Abstract: AIM: To study topical accumulation of aminolevulinic acid in affected parts of moderate to severe acne patients and to determine the optimal liniment concentration,optimal time of beginning lighting and duration time of protecting from light.METHODS: The study was divided into two parts.24 moderate to severe acne patients were divided into three groups in the first part.High,middle and low concentration liniment was given to three groups respectively.Optimal liniment concentration and optimal time of beginning lighting were determined by collecting the facial fluorescence images.8 moderate to severe acne patients were enrolled in the second part. Optimal liniment concentration and optimal initial light time were applied in this part.Plasma and urine samples were also collected to detect concentration of ALA and protoporphyrin Ⅸ.Duration time of protecting from light was determined by collecting the facial fluorescence images.RESULTS: Aminolevulinic acid was absorbed and aggregated in affected parts.Fluorescence intensity reached to approximate maximum during 4-8 h for three groups. Fluorescence intensity of the 10% group is larger than other groups during 4-8 h in the first part.ALA and protoporphyrin Ⅸ were not detected in plasma and urine.Fluorescence intensity in 24 h after clearing the drug approximate 43% comparing with 0 h. Duration time of protecting from light was more than 24 h after clearing the drug.CONCLUSION: Optimal liniment concentration of aminolevulinic acid was 10%.Optimal time of beginning lighting was during 48 h. The optimal time of beginning lighting is 4 h.Duration time of protecting from light was 48 h after clearing the drug.

Key words: Aminolevulinic acid, Moderate to severe acne, Photodynamic therapy, Topical accumulation