Table 3.
Randomized, controlled studies of rifaximin in patients with IBS.
| Study and design | Patients | Treatment | Primary efficacy outcome(s) | Secondary efficacy outcome(s) | Safety |
|---|---|---|---|---|---|
| Rifaximin 550 mg | |||||
| R, DB, PBO-C [Pimentel et al. 2011] | IBS (Rome II criteria) with abdominal pain and discomfort | Rifaximin 550 mg tid (n = 624) versus PBO (n = 634)a for 2 weeks | Adequate reliefb of global IBS symptoms: rifaximin versus PBO: 40.7% versus 31.7% (p < 0.001) | Adequate reliefb of IBS-related bloating: rifaximin versus PBO, 40.2% versus 30.3%, p < 0.001 | AEs comparable between groups Rifaximin versus PBO: Headache: 6.1% versus 6.6% Upper respiratory tract infection: 5.6% versus 6.2% Abdominal pain: 4.6% versus 5.5% |
| R, DB, PBO-C [Pimentel et al. 2014] | IBS-C (Rome II criteria) <3 CSBMs/week and breath methane >3 ppm |
Rifaximin 550 mg tid (n = 16) or PBO (n = 16), both in combination with neomycin 500 mg bid for 2 weeks | Constipation severity 1 week post-tx: rifaximin versus PBO: 28.6 versus 61.2 (p = 0.002) | Baseline to 4 weeks post-tx (rifaximin versus PBO): Constipation severity(p = 0.0007); bloating (p = 0.02); straining (p = 0.02); abdominal pain(p = 0.5) 4 weeks post-tx: Methane ⩽3 ppm: Rifaximin (67%) PBO (69%) |
Rifaximin versus PBO: Nausea: 47% versus 63% Bloating and distension: 47% versus 56% Abdominal pain: 20% versus 38% Constipation: 13% versus 13% Diarrhea: 1% versus 13% Urgency: 0% versus 13% |
| Rifaximin 400 mg | |||||
| R, DB, PBO-C [Pimentel et al. 2006] | IBS (Rome I criteria) | Rifaximin 400 mg tid (n = 43) versus PBO (n = 44) for 10 days | Global improvement in symptoms favored tx with rifaximin versus PBO after 10 weeks (36.4% versus 21%, p = 0.02) | Bloating significantly improved with rifaximin versus PBO after 10 weeks (p = 0.01) No significant improvement in VAS scores for abdominal pain (p = 0.3), diarrhea (p = 0.7), and constipation (p = 0.07) |
Incidence of AEs comparable between groups Most common AEs: abdominal pain, diarrhea, and bad taste in mouth |
| R, DB, PBO-C, CO [Di Stefano et al. 2011] | IBS-C (Rome III criteria) with moderate-to-severe bloating | Rifaximin 400 mg bid versus PBO (n = 24) for 7 days; washout of 4 weeks |
Symptom severity significantly decreased from baseline with rifaximin, but not PBO: Bloating (p = 0.002); abdominal distention (p = 0.03); abdominal pain (p = 0.002); flatulence (p = 0.004); borborygmi (p = 0.008); nausea (NS) Cumulative breath hydrogen excretion significantly decreased from baseline with rifaximin (p < 0.005), but not PBO (NS) |
Not reported | |
a
Patients included in modified intention-to-treat analysis.
b
Defined as relief of symptoms for ⩾2 of first 4 weeks of treatment by self-report.
AE, adverse event; bid, twice daily; CO, crossover; DB, double-blind; CSBM, complete and spontaneous bowel movement; IBS, irritable bowel syndrome; IBS-C, constipation-predominant irritable bowel syndrome; NS, not significant; PBO, placebo; PBO-C, placebo-controlled; ppm, parts per million; R, randomized; tid, 3 times daily; tx, treatment; VAS, visual analogue scale.