A Study in a Human Laboratory Model of Smoking Behavior

The study will be performed in subjects who are heavy cigarette smokers currently not seeking
treatment for tobacco use disorder.

The study is a crossover design study (within-subject analysis), which allows for subjects to
be their own control.

Each period of the crossover consists of a 7-day out-patient treatment period followed by a
single in-patient testing day on Day 8. Subjects will participate in a laboratory session
following the McKee Smoking Lapse Test and be discharged from the clinic to undergo a 7 day
washout period followed by the second period of the crossover design and a 7-day follow-up
visit.

Inclusion Criteria:

1. Provides written informed consent and agrees to complete required clinic visits

2. Male or female 21 to 60 years of age inclusive

3. Body mass index (BMI) 18.5 to 40 kg/m2 inclusive

4. Heavy Smokers

5. Currently not seeking smoking cessation therapy

6. In otherwise good general health without any unstable medical conditions (as
determined by medical history, medication history, physical examination, 12-lead ECG,
vital signs, and clinical laboratory testing)

7. Able to read, write, and speak in English

8. Females must be either:

- Post-menopausal (amenorrhea for at least 12 consecutive months), surgically
sterile -or-

- Women of childbearing potential (WOCBP) must meet the criteria below:

- Uses an acceptable double-barrier method of contraception as determined by
the Investigator -and-

- Is not lactating, has a negative serum beta human chorionic gonadotropin
pregnancy test at screening and a negative urine pregnancy test prior to
dosing on Days 1 and 8 of each treatment period.

9. Male subjects must agree to use a condom if partner is of childbearing potential

Exclusion Criteria:

Subjects meeting the following criteria are not eligible for the study:

1. Any substance use disorder other than nicotine or caffeine as assessed by the
Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) substance
use disorder checklist in addition to the Mini-International Neuropsychiatric
Interview (MINI) (to capture both DSM-V substance use disorder diagnoses)

2. Current neurological conditions that interfere with study conduct, assessment or
treatment in any significant fashion

3. Any lifetime history of bipolar I, II; schizophrenia or any other psychotic disorders;
personality disorders, impulse control disorders as assessed by the MINI

4. Current psychiatric conditions that interfere with study conduct, assessment or
treatment in any significant fashion, such as major depressive disorder (MDD), eating
disorders, post-traumatic stress disorder, etc., without permission of the medical
monitor

5. Recent active or past history of gastric disease such as peptic ulcer disease,
gastritis, upper gastrointestinal bleeding, or any gastrointestinal malignancy or
precancerous condition

6. Active, comorbid disease that might limit the ability of the subject to participate in
the study as determined by the Investigator (i.e., poorly controlled diabetes
mellitus, congestive heart failure, etc.)

7. Clinically significant clinical laboratory test taken during screening, without
permission of the Medical Monitor

8. Elevated AST or ALT ≥ 2 times the upper limit of normal (ULN)

9. Human immunodeficiency virus (HIV), Hepatitis B or Hepatitis C positive as determined
by serology testing at Screening

10. History of severe allergies or multiple adverse drug reactions

11. Known hypersensitivity to CERC-501

12. Current use of a proton pump inhibitor or histamine 2 blocker without permission of
the Medical Monitor

13. Use of any investigational medication within 2 months prior to the start of this study
or scheduled to receive an investigational drug other than the study drug during the
course of this study