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

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.