Refined indigo naturalis ointment was applied topically to one of 2 bilaterally symmetrical psoriatic plaque lesions of the same patient for 8 weeks, starting on the date of enrollment in the study

Crude indigo naturalis ointment was applied topically to one of 2 bilaterally symmetrical psoriatic plaque lesions of the same patient for 8 weeks, starting on the date of enrollment in the study

The patients applied either refined oil extract or crude indigo naturalis ointmnet topically to each of two bilaterally symmetrical psoriatic plaque lesions for 8 weeks.

The PSI score is comprised of the grading for scaling, erythema, and induration on a 5-point scale (where 0=absent, 1=mild, 2=moderate, 3=severe and 4=very severe) and the sum of these three items with a minimal score of 0 and a maximum of score of 12. Higher values represent a worse outcome. For expample, a highter PSI score at baseline and lower PSI score after treatment represent an improvement.

The target plaque area was rated from 0% to 100% (0%=clearance after treatment and 100%=baseline before treatment). Higher values represent a worse outcome. For expample, a lower percentage after treatment represent an improvement.

The improvement percentage of the target plaque at the follow-up visit was calculated as: [(Area of baseline plaque*PSI of baseline plaque - Area of plaque week 8*PSI of plaque week 8)/(Area of baseline plaque*PSI of baseline plaque)]*100%. Higher values represent a better outcome. For expample, a higher percent represents an improvement.

At week 8, patients rated an overall response to treatment (separately for each side of the body), taking into account both the extent and the degree of the disease, compared with the pretreatment condition, on a 6-point scale (0=worse,1=poor, 2=fair, 3=good, 4=excellent, 5=cleared). A score of 4 or higher represents a better outcome.

Two symmetrically comparable plaques on each participant were identified, one randomly assigned to receive refined ointment, and the other assigned to receive crude ointment. Photographs of the lesions were taken and lesion severity was evaluated at baseline and at week 2, 4, 6, and 8.

The PSI score is comprised of the grading for scaling, erythema, and induration on a 5-point scale (where 0=absent, 1=mild, 2=moderate, 3=severe and 4=very severe) and the sum of these three items with a minimal score of 0 and a maximum of score of 12. Higher values represent a worse outcome. For expample, a highter PSI score at baseline and lower PSI score after treatment represent an improvement.

Total number of participants completing the 8 week period with study intervention. The paired t-test was used to compared PSI scores between the two lesions and before treatment with those after treatment.

Crude indigo naturalis ointment was prepared by mixing indigo naturalis powder with olive oil,petroleum jelly and wax.

Erythematous changes occurred at the beginning of treatment and resolved after a couple of days. Patch test results revealed no allergic responses, while monitoring tests for hematology, liver and renal function showed no significant findings.