Efficacy of a Chinese herbal medicine in providing adequate relief of constipation-predominant irritable bowel syndrome : a randomized controlled trial

Background and Aims: Irritable bowel syndrome (IBS) is the most common chronic functional bowel disorder, with few treatment options. IBS affects 10%−20% of the population; as many as 58% of patients have constipation-predominant IBS (IBS-C). We evaluated efficacy and safety of a standardized, specifically formulated Chinese herbal medicine (CHM) preparation in treatment of patients with IBS-C. Methods: We performed a double-blind trial of 125 patients with IBS-C (according to Rome III criteria), recruited from 13 medical centers or clinics in Australia from July 2009 through February 2012. Patients were randomly assigned to groups given a standardized extract of 7 selected CHM ingredients (n=61) or placebo (controls, n=64) for 8 weeks (5 capsules, twice daily). Subjects were then followed for 16 weeks. Chemical definition, standardization, and stability testing of the formulation were completed. Subjects completed a self-administered, validated binary questionnaire of global symptom improvement at weeks 2, 4, 8 and 16 (primary outcome). Secondary outcomes included results from the self-administered an IBS Symptom Severity Scale (IBS-SSS) and the Bristol Stool Form Scale (BSFS), completed at weeks 4, 8 and 16. Results: There was statistically and clinically significant (per protocol analyses) improvement among subjects who received CHM (n=50) vs controls (n=58) for 8 weeks. A greater proportion of subjects receiving the CHM reported adequate relief (P=.010). Compared with controls, the CHM group had improved bowel habits vs controls at week 8, including lower IBS-SSS scores (P<.001), reduced straining during defecation (P=.002), and a significant decrease in hard lumpy stools (P=.031). The CHM group also had increased stool consistency, based on the BSFS (week 8, P<.001). There was no statistically significant difference between groups in abdominal pain at week 8 (P=.692). The CHM was well tolerated. Conclusions: In a prospective, controlled study, CHM reduced symptoms of IBS-C, increased bowel satisfaction and stool consistency, and reduced straining and hard lumpy stools, compared with placebo. Clinical trial registration no: ACTRN12609000558224.