The Effect of Phloroglucinol in Patients With Diarrhea-predominant Irritable Bowel Syndrome: A Randomized, Double-blind, Placebo-controlled Trial.

Background/aims: We aim to evaluate the efficacy and safety of phloroglucinol in patients with diarrhea-predominant irritable bowel syndrome (IBS-D).

Methods: Seventy-two patients with IBS-D who met Rome III criteria were 1:1 randomized in a parallel, double-blind design to receive phloroglucinol or placebo for 2 weeks. Patients were followed for 1 week after the end of treatment. The primary outcome was the proportion of responders, defined as those who answered "moderate or more of improvement" to the subject global assessment for at least 1 week of the 2-week treatment period. Secondary outcomes included the proportion of these patients during the 3-week period including 1 week of follow-up, IBS symptoms (abdominal pain/discomfort, diarrhea, urgency, mucus in stool, bloating, and passage of gas), stool frequency and consistency, and IBS quality of life (IBS-QOL).

Results: The proportion of responders during 2-week treatment period tended to be higher in the phloroglucinol group than in the placebo group, although the difference did not reach statistical significance (55.6% vs 30.6%, = 0.056). The proportion of responders during the 3-week period was significantly higher in the phloroglucinol group than in the placebo group (61.6% vs 30.6%, = 0.013). Individual symptom scores, IBS-QOL, stool frequency and consistency tended to improve in the phloroglucinol group, but there were no statistical significances compared to those of the placebo group. No serious adverse events were reported in both groups.

Conclusions: Phloroglucinol could be a safe and beneficial option for the management of overall IBS symptoms in patients with IBS-D. Further large scaled studies are warranted.