Abstract: Objective To observe the effect of sodium dodecylbenzene sulfonate (SDBS) in killing Demodex in vitro and in the treatment of demodicidosis. Methods ① The experiment of in vitro killing Demodex with 1% and 2% SDBS was conducted. ② A clinical trial was carried out to evaluate the therapeutic effect in the treatment of demodicidosis with 2% SDBS and 2% metronidazole emulsion. Patients with demodicidosis were randomly divided into trial and control groups (31 cases each). They were treated with 2% SDBS ointment and 2% metronidazole ointment twice a day in the early morning and evening respectively for eight weeks consecutively. Inflammatory lesions of face, Demodex infestation and scores of erythema were measured to evaluate the effect before and after treatment. ③ Follow-up was carried out for two months to evaluate the effect and side-effects after 8 weeks' treatment. Results ① 2% SDBS killed all Demodex in vitro after 5h, there was significant difference between the 2% SDBS and 2% metronidazole (69.4%), or between SDBS and peanut oil (9^1%)(P<0.05). There was no significant difference in killing Demodex folliculorum and Demodex brevis with 2% SDBS. ② Clinical observation showed that there was a significant difference in facial inflammatory lesions, Demodex infestation and scores of erythema before and after treatment with 2% SDBS(P<0.05). The effective rate was 87^1%, 65^5% in 2% SDBS group and 2% metronidazole group respectively, with a significant difference between the two groups (P<0.05). Follow-up showed same results. ③ A slight burning sensation was the only side-effect in 3 cases with 2% SDBS ointment. Conclusion Sodium dodecylbenzene sulfonate has the effect of in vitro killing Demodex and is highly effective in the treatment of demodicidosis.

Key words: Demodicidosis, Sodium dodecylbenzene sulfonate, Treatment outcame