Conditions: Irritable Bowel Syndrome With Diarrhea
Keywords: IBS IBS-D IBS with diarrhea Diarrhea Irritable bowel syndrome with diarrhea
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 2583
Healthy volunteers: no

Brief summary:
This study will evaluate the effectiveness and safety of repeat treatment with rifaximin 550 mg three times a day in patients with IBS with diarrhea who respond to initial treatment of rifaximin 550 mg three times a day.

Detailed description:
It is important in chronic conditions to have information about how a product that is intended for short course administration in order to confer prolonged benefit should be administered beyond the first cycle of use once symptoms reappear. This Phase 3 study will evaluate the efficacy and safety of repeat treatment with rifaximin 550 mg three times daily (TID) for 14 days in subjects with IBS-D who respond to an initial treatment course with rifaximin 550 mg TID for 14 days.

This study consists of several treatment phases outlined below:

Screening/Treatment 1 Phase. Subjects will receive single-blind placebo TID for 7-13 days and answer daily IBS symptom-related questions.

Treatment 2 Phase. Eligible subjects will receive open-label rifaximin 550 mg TID for 2 weeks with a 4-week treatment-free follow-up. Responders will continue into Maintenance Phase 1. Nonresponders will withdraw from the study.

Maintenance Phase 1. Subjects will continue the treatment-free follow-up period for up to 18 weeks until either: 1) they experience recurrence or 2) enrollment is met in the Treatment 3 Phase (Double Blind Repeat Treatment Phase). Subjects who do not meet recurrence criteria by the end of the Maintenance Phase 1 will withdraw from the study.

Treatment 3 Phase/ Double Blind Repeat Treatment Phase. Subjects who meet criteria for recurrence will be randomized 1:1 to receive either rifaximin 550 mg TID or placebo TID for 2 weeks with a 4-week treatment-free follow-up.

Primary efficacy analysis will be performed at the end of the Treatment 3 Phase (at Week 6 of the double-blind period).

Maintenance Phase 2. All subjects continued into an additional treatment-free follow-up period of up to 6 weeks (Maintenance Phase 2).

Treatment 4 Phase/Second Repeat Treatment Phase. Subjects will receive the same double-blind treatment as previously assigned in the Treatment 3 Phase for 2 weeks with a 4-week treatment-free follow-up.

A lactulose breath test sub-study will be conducted at select sites.

Arms:
arm 1: Subjects will receive open-label rifaximin 550 mg TID for 2 weeks with a 4-week treatment-free follow-up. Responders will continue into Maintenance Phase 1 (treatment free). Nonresponders will withdraw from the study.

Subjects who meet criteria for recurrence in Maintenance Phase 1 enter the double-blind period and are randomized 1:1 to receive rifaximin 550 mg or placebo. arm 2: Subjects in this arm receive rifaximin 550 mg TID for 2 weeks with a 4-week treatment-free follow-up (first retreatment) followed by Maintenance Phase 2 (6 weeks \[treatment free\]) followed by a second retreatment with rifaximin 550 mg TID for 2 weeks with a 4-week treatment-free follow-up. arm 3: Subjects in this arm receive placebo TID for 2 weeks with a 4-week treatment-free follow-up (first retreatment) followed by Maintenance Phase 2 (6 weeks \[treatment free\]) followed by a second retreatment with placebo TID for 2 weeks with a 4-week treatment-free follow-up.

Interventions: intervention 1: open-label rifaximin intervention 2: double-blind placebo intervention 3: double-blind rifaximin
Intervention descriptions: intervention 1: 550 mg three times a day (open-label) intervention 2: 3 times a day (double-blind) intervention 3: 550 mg three times a day (double-blind)

Protocol document: