An Extension Study to Examine the Safety and Tolerability of a New Drug in Patients With Symptoms of Overactive Bladder (OAB).

Inclusion Criteria:

1. Has completed participation in study RVT-901-3003.
2. Has demonstrated ≥ 80% compliance with self-administration of Study Treatment in studyRVT-901-3003.

Exclusion Criteria:

1. Has a change in history or current evidence of any clinically significant condition,therapy, lab abnormality, or other circumstance that might, in the opinion of theInvestigator, confound the results of the study, interfere with the participant'sability to comply with study procedures, or make participation in the study not in theparticipant's best interest.
2. Has coronary or neurovascular interventions planned during the duration of the study.
3. Has uncontrolled hyperglycemia (defined as fasting blood glucose >150 mg/dL or 8.33mmol/L and/or non-fasting blood glucose >200 mg/dL or 11.1 mmol/L) based on mostrecent available lab results in study RVT-901-3003 or, if in the opinion of theInvestigator, is uncontrolled.
4. Has uncontrolled hypertension (systolic blood pressure of ≥ 180 mm Hg and/or diastolicblood pressure of ≥ 100 mm Hg) or has a resting heart rate (by pulse) > 100 beats perminute.
5. Has clinically significant ECG abnormality which, in the opinion of the Investigator,exposes the participant to risk by participating in the study
6. Has alanine aminotransferase or aspartate aminotransferase > 2.0 times the upper limitof normal (ULN), or bilirubin (total bilirubin) > 1.5 x ULN (or > 2.0 x ULN ifsecondary to Gilbert syndrome or pattern consistent with Gilbert syndrome) based onmost recent available lab results in study RVT-901-3003.
7. Has an estimated glomerular filtration rate (eGFR) < 30mL/min/1.73 m2 based on mostrecent available lab results in study RVT-901-3003.
8. Use of any prohibited medications as detailed in Section 7.7.3.
9. Plans to initiate or change the dosing of any medications listed in Section 7.7.5during the study that in the opinion of the investigator is assessed to be clinicalsignificant.
10. Has an allergy, intolerance, or a history of a significant clinical or laboratoryadverse experience associated with any of the active or inactive components of thevibegron formulation or tolterodine formulation.
11. Is currently participating or has participated in a study with an investigationalcompound or device within 28 days of signing informed consent, not includingparticipation in study RVT-901-3003.
12. Has a history of significant drug or alcohol abuse/dependence within a year ofinformed consent, as assessed by the investigator.
13. Has a varying sleep schedule anticipated during times when the voiding diaries are tobe completed.