Divalproex ER vs. Risperidone for Bipolar Disorder With Comorbid Substance Use Disorder

Inclusion Criteria: * Signed written informed consent for trial participation. * Male or female patients, ages 19-65. * Patients must meet DSM-IV criteria for bipolar I or bipolar II disorder (any phase of illness) and concurrent substance use disorder (alcohol or illicit drug abuse or dependence). * Female patients of childbearing potential must be using a reliable method of contraception. Reliable methods of contraception include hormonal contraceptives (oral contraceptive or long-term injectable or implantable hormonal contraceptive), barrier methods (e.g., condom and diaphragm, condom and foam, condom and sponge), intrauterine devices, and tubal ligation. * Female patients of child-bearing potential must have a negative urine pregnancy test at screening. * Patients must not have other serious unstable illnesses and must be otherwise physically stable on the basis of a physical exam, medical history, and the results of blood biochemistry, hematology tests, and a urinalysis. * Patients must complete at least a 48-hour wash screening/washout period for mood stabilizers and oral neuroleptics.The wash screening/washout period may be completed as an inpatient. If so patient may remain an inpatient as long as necessary. Should the patient become discharged he or she must be able to continue in the study as an outpatient. Exclusion Criteria: * Patients with a current DSM-IV diagnosis of schizophrenia or schizoaffective disorder. * Patients who are legally incompetent * Receiving any other psychotropic medication within 48 hours of randomization, excluding trazodone for insomnia. * Patients with Axis I or Axis II diagnosis that in the investigator's opinion, would interfere with compliance or confound interpretation of the results. * Patients with CNS neoplasm, uncontrolled metabolic, endocrine, demyelinating or progressive neurological disorder, pancreatitis, or urea cycle disorder. * Patients with a blood chemistries ALT and/or AST value(s) greater than or equal to three times the upper limit of normal prior to randomization. * Patients with a history of a chronic or acute medical disorder that, in the opinion of the investigator, would confound interpretation of the study results. * Patients with a medical condition that requires the continuous use of medication that would interfere with the evaluation of safety or efficacy of divalproex ER or risperidone. Patients receiving beta-blockers are excluded unless the dose has been stable for greater than 6 months. * Patients who have received depot neuroleptic medication within one inter-injection interval of randomization. Patients on depot medications may be included if they are randomized no earlier than the time of their next scheduled depot injection. * Patients who exhibits signs of drug or alcohol withdrawal at the time of randomization. * Patients that require the use of naltrexone or disulfiram during the study. * Patients with a history of previous severe intolerance, idiosyncratic reaction or allergies related to valproate or risperidone. * Patients with a history of failed treatment on adequate valproate or risperidone therapy for bipolar disorder in the opinion of the investigator. * Patients who have taken Divalproex DR, Divalproex ER, or risperidone regularly over the 30 days prior to screening/washout. If patients have taken divalproex (either DR or ER) at all in the 30 days prior to screening/washout, a serum valproate level must be done at the time of screening and found to be below the minimum quantifiable limit. * Women who are pregnant or intends to become pregnant. * Patient with a platelet count at screening \<100,000/mL. * Patients with serious violent, homicidal, or suicidal ideation.