The primary outcome measure is assessed during the 4-week period (ie, Weeks 3 through 6) immediately following 2 weeks of treatment with study drug. Adequate relief of global IBS symptoms was defined as a response of "yes" to the following question, which was asked weekly (every 7 days): "In regard to all your symptoms of IBS, as compared to the way you felt before you started study medication, have you, in the past 7 days, had adequate relief of your IBS symptoms? \[Yes/No\]"

A summary of serious and all other non-serious adverse events, regardless of causality, is located in the Reported Adverse Events module.

Time to a breakthrough overt HE episode was the duration (number of days) from time of first dose of study drug to the first breakthrough overt HE episode. A breakthrough overt HE episode was defined as an increase of Conn score from Grade 0 or 1 to ≥2, or an increase in Conn and asterixis score of 1 grade each for those participants who entered the study with a Conn score of 0. Participants who completed the study and did not experience a breakthrough overt HE episode were censored at the time of their 6-month visit. Participants who terminated early for reasons other than a breakthrough overt HE episode were contacted at 6 months from randomization to determine if they had experienced a breakthrough overt HE event or other outcome. Participants without breakthrough overt HE were censored at the time of last contact or death, whichever was earlier. The number of events of a first breakthrough overt HE episode during the treatment interval is presented.

Resolution or improvement of baseline signs and symptoms was assessed as * Absence of severe abdominal pain for 2 consecutive days at the test of cure (TOC) Visit (Day 14 +/-1); * Absence of fever (\< 38°C/100.4°F) for 2 consecutive days at the TOC Visit; and * 3 unformed (loose or watery) stools per day for at least 48 hours that was sustained through the TOC Visit.

The efficacy of 14 days of rifaximin 600 mg once daily (QD) compared with placebo when taken by healthy subjects to prevent travelers' diarrhea (TD) resulting from all causes.