Comparison of indirubin concentrations in indigo naturalis ointment for psoriasis treatment: a randomized, double ‐blind, dosage‐controlled trial

Summary Corticosteroids are commonly used topical (applied to the skin) therapies in psoriasis; although beneficial, there are concerns about their prolonged use and there is a need for effective alternatives. Many herbal remedies have been used topically, although evidence for their benefit is often limited. Indigo naturalis has been used for several years in Chinese traditional medicine; unfortunately, when taken by mouth it can cause gastro‐intestinal side effects or liver damage. Previous studies have shown it may be effective, as a crude ointment or a refined preparation, containing the active ingredient indirubin, which causes less skin staining than the crude preparation. Indirubin has anti‐inflammatory properties and reduces the excessive turnover of cells called keratinocytes in the outermost layer of skin, the epidermis, which is seen in psoriasis. The authors, based in Taiwan, aimed to find the optimal concentration of indirubin in a topical preparation. They recruited 109 adults with psoriasis affecting less than 20% body surface area. The subjects received different concentrations of indirubin (ranging from 10 to 200 μg/g) for an 8 week treatment period, followed by a further 12 week monitoring period. The researchers measured the Psoriasis Area and Severity Index (PASI) before and after treatment, which is a measurement of how severe a person's psoriasis is. 200 μg/g was the most effective concentration: in this group 56.5% of patients achieved a 75% i...
Source: British Journal of Dermatology - Category: Dermatology Authors: Tags: Plain Language Summary Source Type: research