A Single-Dose, Open-Label, Study to Evaluate the Sustainability of the Effects of SYN-010 in Patients With IBS-C

This is a Phase 2, multi-center, open-label study. Up to sixty subjects with irritable bowel
syndrome with constipation who are between the ages of 18 and 65, inclusive, will be
enrolled. Subjects must have completed the previous SB-2-010-001 study. The entire duration
of the study may be up to 57 days (from enrollment to the post end-of-study [EOS] visit
telephone call).

Inclusion Criteria:

- Subject has completed Study SB-2-010-001.

- Subject must be willing to abstain from or discontinue the use of any laxatives and
any prescription and over-the-counter medications or supplements intended to treat
constipation from the time of Screening to the end of the study, except as permitted
in this protocol.

- Subject must agree to refrain from making any lifestyle changes that may affect IBS-C
symptoms from the time of Screening to the end of the study.

Exclusion Criteria:

- Subject has taken IBS treatments (prescription or over-the-counter), proton pump
inhibitors, laxatives, antibiotics.

- Subject did not complete Study SB-2-010-001 or more than 7 days have elapsed since the
subject's last dose of study drug in that study.

- Subject reports loose (mushy) or watery stools (Bristol Stool Form Scale [BSFS] score
of 6 or 7) in the absence of any laxative, or has a BSFS score of 6 for more than 1
spontaneous bowel movement (SBM) or a BSFS score of 7 for any SBM during the last 7
days of diary reporting for Study SB-2-010-001.

- Subject has any abnormal laboratory results, electrocardiogram (ECG) findings, or
physical examination findings deemed clinically significant by the investigator at the
Study SB-2-010-001 End-of-Study Visit.