The primary purpose of this study is to determine the safety and efficacy of oral RG2417 (Uridine) when administered to patients with Bipolar I depression twice daily for six weeks.

Inclusion Criteria:

1. DSM-IV-TR diagnosis of Bipolar I Depression
2. 18 to 65 years of age, inclusive
3. Depressive phase, as measured by MADRS greater than or equal to 20 at Screening and Day1
4. Duration of current depressive episode of at least four weeks by Day 1
5. Competent to give informed consent

Exclusion Criteria:

1. Manic/hypomanic/mixed episode as determined by the MINI at Screening and/or a Young Mania Rating Scale (YMRS) score of > 12 at Screening and/or Day 1
2. Dementia or any current Axis I diagnosis (excluding bipolar I) requiring pharmacological treatments
3. A history of alcohol or substance dependence within six months of Day 1, or a history of alcohol or substance abuse within three months of Day 1
4. Urine drug screen positive for amphetamines, cocaine metabolites, opiates and/or phencyclindine (PCP)
5. An Axis II diagnosis that is likely to interfere with protocol compliance
6. Initiation of or increase in psychotherapy within 4 weeks of Screening
7. Psychotropic medication (excluding fluoxetine) within 24 hours of initiation of study drug on Day 1; fluoxetine within 2 weeks of initiation of study drug on Day 1
8. Serious suicidal or homicidal risk as determined by the investigator and/or a score of > 5 on the suicide item #10 of the MADRS at Screening and/or Day 1
9. History of sensitivity to any of the ingredients in the study drug
10. Clinically significant abnormality in any screening laboratory results
11. Clinically significant organic disease, including cardiovascular, endocrine, hepatic, pulmonary, neurologic, or renal disease, or any other medical condition, serious intercurrent illness, or extenuating circumstances that, in the opinion of the investigator, would interfere with the performance or interpretability of, or put the patient at risk from, the study procedures
12. Women who are pregnant, breastfeeding, or refuse to use adequate birth control
13. Current seizure disorder
14. Participation in an investigational drug study within twenty-eight days of Day 1
15. Current psychotic episode
16. Clozaril use and/or electroconvulsive therapy within six months of Day 1
17. Failure of three or more adequate trials of standard therapies for depression during the current episode
18. Current episode of depression is longer than one year