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 1 month after the last dose of
study medication.

- They are able to understand and sign a written informed consent form, which must be
obtained prior to initiation of study procedures.

Exclusion Criteria:

- They have documented history of proximal or universal ulcerative colitis, proctitis
or active proctitis confined to 15cm or less from the anal verge.

- They demonstrate signs and symptoms of fulminant colitis, bowel stricture, toxic
megacolon, an anticipated need for blood transfusion for gastrointestinal bleeding,
or demonstrate evidence of peritonitis.

- They receive a Physician's rating of disease severity as part of the modified UCDAI
of 3 (severe disease) or an aggregate score of 11 or greater.

- They have shown prior documented history of evidence of high grade dysplasia on
biopsy from endoscopic examinations.

- Their stool contains enteric pathogens or Clostridium difficile toxins.

- They have a history of recurrent Clostridium difficile infection.

- They have prior history of biologic therapy within the previous 4 years.

- They have received systemic steroids or immunosuppressants within the previous 4
weeks.

- Treatment in the last 14 days that included antibiotic, antifungal, antiparasitic
medications, or rectally administered steroids (e.g. Cortenema®) or mesalamine enema
(Rowasa®).

- Treatment in the last 7 days that included mesalamine (5-ASA) via oral administration
(e.g. Asacol®, Lialda®, balsalazide, etc).

- They have a history of cancer (defined as malignancy within 5 years except for
squamous cell or basal cell cancers of the skin), asthma, or bronchospasm.

- Positive pregnancy test or lactating subjects.

- There is evidence of chemical substance abuse.

- They have had repeated anti-inflammatory drug treatment (longer than 3 days at doses
that exceed those available without a prescription) within the previous 7 days (with
exception of aspirin at doses of 325mg/day or less for prophylaxis of cardiac
disease), or initiated new non-steroidal anti-inflammatory (NSAID) treatment within
the last 30 days.

- They have a known allergy to N-acetylcysteine or mesalamine, or have a history of
serious AEs related to their use (including, but not limited to pancreatitis or
hepatitis).

- They have a history of failure to retain enemas.

- Other clinically significant diseases that could interfere with the protocol
compliance appear. These would include clinically important hematological, renal,
hepatic, metabolic, psychiatric, central nervous system (CNS), pulmonary or
cardiovascular disease.

- Use of any investigational medication within the previous 90 days.

- Any condition which the study physician judges to preclude safe participation in the
study or to confound the evaluation of the study outcome.