MAINTENANCE EFFICACY OF ORAL INDIGO NATURALIS FOR ULCERATIVE COLITIS: A SINGLE-CENTER, OPEN-LABEL, RANDOMIZED, CONTROLLED STUDY

Abstract

Abstract BACKGROUND Indigo naturalis (IN) is one of the herbal medicines in Chinese medicine. Recent reports have demonstrated a strong remission induction efficacy of oral IN in induction therapy for ulcerative colitis (UC), but the efficacy of IN in maintenance therapy for UC is unknown. OBJECTIVES We aimed to clarify the maintenance effect of IN. METHODS A single-center, open-label, randomized, controlled trial was conducted from August 2017 to August 2020. Patients with UC who received induction therapy with IN and maintenance therapy with IN for at least 1 year were enrolled. Patients with endoscopically confirmed mucosal healing (Mayo endoscopic subscore 0 or 1) were randomized. Patients were randomized to continue or discontinue IN. The primary endpoint was the remission rate at 52 weeks after discontinuation. Patients who relapsed during the observation period were given additional therapy, and remission rates were examined for patients who received an increased dose of IN or resumed oral therapy. The study was registered in the University Hospital Medical Information Network Center Trials registry, UMIN000028574. RESULTS A total of 20 patients participated in this study, 10 in the IN-continued group and 10 in the IN-discontinued group. The median age was 32.5 years and 33.5 years in the IN-continued group and IN-discontinued group, respectively, and 6 and 5 patients were male. Two patients in the IN-continued group and three patients in the IN-discontinued group were treated with azathioprine. One patient in the IN-continued group and three patients in the IN-discontinued group were treated with anti-tumor necrosis factor therapy. The remission rates at 52 weeks were 90% (9/10) of patients in the IN-continued group and 20% (2/10) in the IN-discontinued group. The remission rate was significantly higher in the IN-continued group (p = 0.0055). Of the 9 patients who relapsed, 7 were treated with increased or resumed oral IN, and all patients were induced remission again. No serious adverse events were observed during the observation period. CONCLUSIONS IN appears to be very effective in maintaining remission; the high efficacy of reintroduction in patients who relapsed after discontinuation of IN suggests that discontinuation of IN in cases of remission may be an option.