This study will determine the maximum tolerated dose (MTD) of arbaclofen placarbil (AP) in the treatment of subjects with Alcohol Use Disorder (AUD). For every two subjects receiving AP, one subject will receive placebo.

This is a randomized, double-blind, placebo-controlled dose-escalation study to determine the MTD of AP in subjects with AUD. Eighteen (18) subjects will be randomized to receive either AP or placebo in a 2:1 ratio; ie, 12 subjects will be assigned to AP and 6 will be assigned to placebo. Efforts will be made to enroll all subjects in the same period of time at one clinical center. The expected maximum duration of participation for each subject is 11 weeks and will consist of up to a 3-week screening period, up to a 30-day residential (inpatient) treatment period, up to a 4-week non-residential (outpatient) treatment period, and an end of study / early termination clinic visit.

Inclusion Criteria:

1. 18 to 65 years of age.
2. Diagnosis of AUD confirmed by the Mini-International Neuropsychiatric Interview.
3. For those requiring medical detoxification from alcohol, subjects will be required to have completed a program for detoxification from alcohol within 4 days prior to screening.
4. Provide written informed consent prior to any study-specific procedures.
5. Self-report of at least 2 heavy drinking days per week in each of the 4 weeks prior to the screening interview.
6. Willing to abstain from drinking for the time he/she is participating in the study.
7. Able to identify at least 1 "locator" person to assist study staff in tracking the subject for the non-residential clinic days.
8. Able to read, speak, and understand English and be willing to cooperate with study procedures.
9. For female subjects, women of childbearing potential must have a negative pregnancy test prior to enrollment and must agree to use a medically acceptable means of contraception from screening through at least 3 months after the last dose of IMP. Male subjects with female partners of childbearing potential must agree to use medically acceptable contraception from informed consent through at least 3 months after the last dose of IMP. Male subjects must also agree not to donate sperm during the study and for 3 months after receiving the last dose of IMP (Investigational Medicinal Product).

Exclusion Criteria:

1. Has present symptoms or history of any of the following disorders:

   • Schizophrenia
   • Schizoaffective Disorder
   • Delusional Disorder
   • Bipolar I Disorder
   • Any mood disorder with psychotic features or any psychotic disorder
   • Anorexia Nervosa
   • Bulimia Nervosa
   • Post-Traumatic Stress Disorder that could interfere with the study
   • Any Personality Disorder that could interfere with the study

2. Current diagnosis of any substance use disorder, except for nicotine, cannabis (mild or moderate), or alcohol.

3. Positive result for any prohibited medication.

4. History of suicidal ideation within 30 days prior to providing written informed consent.

5. History of seizures or delirium tremens.

6. Intention to initiate or continue additional formal alcohol-related treatment, including pharmacotherapy, during the active treatment period.

7. Have had inpatient treatment for a non-alcohol substance use disorder in the 12 weeks prior to informed consent.

8. Total bilirubin >1.5× the upper limit of normal (ULN), alanine aminotransferase (ALT) >3×ULN, aspartate aminotransferase (AST) >3×ULN, serum creatinine >2×ULN, international normalized ratio (INR) >1.5×ULN, lipase >3×ULN, amylase >3×ULN, or any abnormal pancreatic enzyme value above ULN that is associated with clinically significant active pancreatic disorder.

9. Creatinine clearance of <80 mL/min, as calculated according to the Cockcroft-Gault equation.

10. Hemoglobin at screening of <11.5 g/dL (for females) or <12.5 g/dL (for males).

11. Body mass index (BMI) >30.

12. Diagnosed with unstable medical disorders that could increase the potential risk of study treatment or interfere with study participation, including the following:

    1. Abnormal cardiac conditions, including:

       • Uncontrolled hypertension.
       • History of myocardial infarction in the last year or any prior history of myocardial infarction with active complication.
       • Syncopal event within the past year.
       • Congestive heart failure.
       • Angina pectoris.
       • QTcF (QT Fridericia-corrected) ≥450 msec for males and ≥470 msec for females at screening or randomization.
       • Clinically significant abnormal finding on the physical exam or 12-lead ECG.

    2. Diabetes mellitus (type 1 or 2) fulfilling any of the following criteria:

       • Glycosylated hemoglobin (HbA1c) >7.5% at screening.
       • Uncontrolled diabetes mellitus.

13. Have any other clinically significant abnormal laboratory result

14. Must not have donated blood or have had any therapeutic phlebotomy (in an amount >300 mL) or received blood transfusion within 90 days preceding enrollment.

15. Must not have a history of surgical procedures involving the brain or meninges, encephalitis, meningitis, degenerative central nervous system disorder (eg, Alzheimer's or Parkinson's Disease), epilepsy, mental retardation, or any other disease/procedure/accident/intervention associated with significant injury to or malfunction of the central nervous system (CNS), or a history of significant head trauma within the past 2 years, or currently receiving anticonvulsant therapy for any reason.

16. Must not have acquired immunodeficiency syndrome (AIDS).

17. Have any other active medical condition or organ disease that may either compromise subject safety or interfere with the safety and/or outcome evaluation of the IMP.

18. History or presence of allergic or adverse response (including rash or anaphylaxis) to baclofen or any ingredient of the IMP.

19. Have used baclofen within 30 days prior to informed consent.

20. Taking medications which may be expected to significantly interfere with the metabolism or excretion of AP, may be associated with a significant drug interaction with AP, or may pose a significant risk to the subject's participation in the study.

21. Participation in an interventional clinical study within 30 days prior to informed consent.

22. Use of exclusionary drugs (e.g. antipsychotics, anticonvulsants, benzodiazepines, naltrexone, acamprosate).

23. Site staff or subjects affiliated with, or a family member of, site staff directly involved in the study.

24. Be unable to comply fully with the study requirements.