Study of the Safety and Efficacy of Zoenasa® Versus Mesalamine Enema in Subjects With Left-Sided Ulcerative Colitis

Inclusion Criteria: * Male and female subjects are eligible if they are ≥ 18 years of age and ≤ 64 years. * They have a documented history of idiopathic ulcerative colitis based on endoscopic and/or histologic findings involving the left side of the colon, with mild to moderate active disease. * Eligible subjects will have a documented history of ulcerative colitis, and a modified UCDAI score of 4-10, inclusive, with a Physician's rating of disease score of 2 points or less (mild or moderate active ulcerative colitis), rectal bleeding score of 1 or more (based on subject diary), and mucosal appearance score (based on endoscopy) of 1 point or more at baseline. * Laboratory data: * White blood cell count between 4.0 - 12.0 K/mm3 * Platelet count: 150 - 500 K/mm3 * Hemoglobin \> 10.0 g/dL * Total bilirubin \< 1.5 mg/dL * Aspartate aminotransferase \< 100 u/dL * Alanine aminotransferase \< 100 u/dL * Alkaline phosphatase \< 250 u/dL * Blood urine nitrogen \< 40 mg/dL * Creatinine \< 1.5 mg/dL * Satisfies one of the following: * Female subjects of childbearing potential must have a negative urine pregnancy test at screening; surgically sterile, post-menopausal, abstinent, or patient or partner agree to use a medically appropriate form of birth control from screening to until 1 month after the last dose of study medication. * Male subjects must be surgically sterile, abstinent, or patient or partner compliant with a contraceptive regimen from screening to until …