Table 1.
Studies of rifaximin in patients with IBS
| Study and design | No of participants | Primary and secondary outcomes | Rifaximin dose and duration | Results | Limitations |
|---|---|---|---|---|---|
| Sharara et al36 P, R, DB, PC |
N=124 Rifaximin =63 Placebo =61 |
Primary: global IBS symptom improvement Secondary: change in LHBT, composite 10-day symptom score |
400 mg bid for 10 days | Higher global improvement in IBS symptoms with rifaximin (41.3% vs 22.9%, P=0.03). Lower mean symptoms score and bloating with rifaximin (P=0.01). No significant change in LHBT overall with rifaximin. Significant drop in LHBT in responders to rifaximin vs non-responders, and correlated with bloating and overall symptom scores (P=0.01) | Only 54% and 59% of participants in each group fulfilled Rome II criteria for IBS; single center |
| Pimentel et al50 P, R, DB, PC |
N=87 Rifaximin =43 Placebo =44 |
Primary: global IBS symptoms Secondary: abdominal pain, bloating, diarrhea, and constipation |
400 mg tid for 10 days | Higher global improvement in IBS symptoms with rifaximin (36.4% vs 21%, P=0.02). Bloating improved with rifaximin (P=0.01). Abdominal pain, diarrhea, and constipation were not significantly different |
Most patients were from a single center; short duration |
| Meyrat et al15 P |
N=106 | LHBT Overall well-being, bloating, diarrhea, flatulence, and abdominal pain |
200 mg qid for 14 days | 71% were LHBT positive Improved overall well-being (3.9% vs 2.7%, P<0.001), bloating (5.5% vs 3.6%, P<0.001), flatulence (5% vs 4%, P=0.015), diarrhea (2.9% vs 2%, P=0.005), and abdominal pain (4.8% vs 3.3%, P<0.001) |
Lack of control group; unblinded |
| Pimentel et al37 P, R, DB, PC |
N=1,260 TARGET 1: Rifaximin =309 and placebo =314 TARGET 2: Rifaximin =316 and placebo =321 |
Primary: global IBS symptom relief for at least 2 of 4 weeks Secondary: adequate relief of bloating, abdominal pain, and discomfort |
550 mg tid for 14 days | Higher global improvement in IBS symptoms with rifaximin (40.8% vs 31.2%, P=0.01, TARGET 1; 40.6% vs 32.2%, P=0.03, TARGET 2; and 40.7% vs 31.7%, P<0.001, combined). Rifaximin group had more relief of bloating (39.5% vs 28.7%, P=0.005, TARGET 1; 41.0% vs 31.9%, P=0.02, TARGET 2; and 40.2% vs 30.3%, P<0.001, combined) and abdominal pain/discomfort (44.3% vs 36.3%, P=0.03, TARGET 1 and 42.9% vs 34.4%, P=0.02, TARGET 2) |
Only included IBS without constipation |
| Pimentel et al38 P, R, DB, PC |
N=31 Neomycin =16 Neomycin and rifaximin =15 |
Primary: constipation severity Secondary: overall constipation severity, straining, bloating, and abdominal pain |
Neomycin (500 mg bid) + placebo Neomycin 500 mg bid and rifaximin (550 mg tid) for 14 days |
Lower constipation severity with addition of rifaximin (28.6 mm vs 61.2 mm, P=0.0042). Greater improvement in straining (P=0.017) and bloating (P=0.020), but not abdominal pain | IBS-C only; combined systemic and non-absorbable antibiotics |
Abbreviations: IBS, irritable bowel syndrome; No, number; P, prospective; R, randomized; DB, double blind; PC, placebo controlled; LHBT, lactulose hydrogen breath test; bid, twice daily; tid, three times a day; qid, four times a day; TARGET, targeted, nonsystemic antibiotic rifaximin gut-selective evaluation of treatment for non-c irritable bowel syndrome; IBS-C, constipation-predominant IBS.