Efficacy Study of RX-10100 to Treat Major Depressive Disorder (MDD)

- Males or females between 18 and 65 years old

- Diagnosis of MDD using DSM-IV criteria

- Have a score of 20 or more on the HAM-D-17

- Have a score of 4 or more on the CGI-S

- Written informed consent obtained

- Have a negative serum (P-HCG) pregnancy test at screening (for all women)

- Female subjects must meet one of the following criteria: (a) Be surgically sterile or (b) Agree that, if sexually active they will use oral contraceptives, double barrier contraception (E.g., condom with spermicide), intrauterine device, or other method approved by the sponsor.

- Have a BMI > 40 or < 18

- Unstable angina pectoris

- History of myocardial infarction, stroke, or life-threatening arrhythmia within the prior 6 months

- Uncontrolled atrial fibrillation/flutter at screening

- Severe chronic or acute liver disease; history of moderate or severe hepatic impairment

- Clinically significant chronic hematological disease which may lead to priapism, such as sickle cell anemia and leukemia

- Bleeding disorder

- Resting hypotension or hypertension

- History of malignancy (cancers) within the past 5 years (other than squamous or basal cell skin cancer)

- NYHA Class III or IV heart failure

- Substance abuse/dependence within the past 6 months

- Significant suicidal ideation based on the C-SSRS

- Other current nondepressive Axis I disorders

- Depressive episode duration of less than 1 month or greater than 9 months

- Bipolar disorder

- Dysthmic disorder

- Borderline personality disorder

- Psychotic disorder/current psychotic features

- Any abnormal findings on the screening ECG judged clinically significant by the Investigator

- Any medical condition that is not stabilized or is anticipated to require hospitalization within 6 months, in the opinion of the Investigator

- Any history of cholestatic jaundice or liver cirrhosis

- Hyper- or hypothyroidism unless the subject has received a stable dose of thyroid medication for at least 3 months prior to the screening visit

- Women, who are breast-feeding, have been lactating within 3 months prior to screening

- Concurrent psychotherapy

- Subjects who have received any other investigational drug (including placebo) within 30 days before Visit 1

- Use of any treatment for MDD within 7 days of Visit 1 (14 days for fluoxetine) and during the study other than the study medication

- Use of antidepressants, anxiolytics, or other psychoactive drugs within 14 days of Visit 1 and during the study

- Concomitant use of antibiotics in the penicillin class (for the reduction of the potential for any additive or synergistic hepatotoxicity)

- A positive urine drug screen

- Elevation of AST and/or ALT > 3 times the upper limit of normal (ULN)

- Diabetic subjects with an HbAlc ≥ 12%

- Any abnormal screening laboratory values judged clinically significant by the Investigator

- Previous nonresponse or hypersensitivity to two or more trials of antidepressant medication given in adequate doses and duration for the treatment of symptoms present in the current illness

- Subjects with known hypersensitivity to any antibiotic in the penicillin class

- Subjects who are illiterate or unable to understand the questionnaires

- Subjects who, in the opinion of the investigator, would be non-compliant with the visit schedule of study procedures

- Subjects who pose potential harm to others