Objective: To evaluate the efficacy and safety of treatment with indigo naturalis in patients with recalcitrant plaque-type psoriasis.
Design: Randomized, observer-blind, vehicle-controlled, intrapatient comparison study.
Setting: Ambulatory department of a hospital.
Participants: Forty-two outpatients with chronic plaque psoriasis were enrolled in the study from May 1, 2004, to April 30, 2005.
Intervention: The patients applied either indigo naturalis ointment or vehicle ointment topically to each of 2 bilaterally symmetrical psoriatic plaque lesions for 12 weeks (depending on the date of enrollment in the study).
Main outcome measures: The outcomes were assessed using the following criteria: the sum of erythema, scaling, and induration scores and the clearing percentage of the target plaque lesion assessed by 2 blinded observers.
Results: Significant reductions in the sum of scaling, erythema, and induration scores (P < .001) (mean score, 6.3 after indigo naturalis treatment vs 12.8 in control subjects) and plaque area percentage (P < .001) (mean percentage, 38.5% after indigo naturalis treatment vs 90% in controls) were achieved with topical application of indigo naturalis ointment. Approximately 31 of 42 patients (74%) experienced clearance or near clearance of their psoriasis in the indigo ointment-treated lesion.
Conclusion: Topical indigo naturalis ointment was a novel, safe, and effective therapy for plaque-type psoriasis.