A Safety and Efficacy Study of Naltrexone SR/Bupropion SR and Placebo in Overweight and Obese Subjects Participating in an Intensive Behavior Modification Program

Inclusion Criteria: * Female or male subjects aged 18 to 65 years (inclusive) * Body mass index (weight \[kg\]/height \[m²\]) ≥30 and ≤45 kg/m² for subjects with uncomplicated obesity, and BMI of ≥27 and ≤45 kg/m² for subjects with controlled hypertension and/or dyslipidemia * Non-smoker and had not used tobacco or nicotine products for at least 6 months before screening * Normotensive (systolic ≤140 mm Hg and diastolic ≤90 mm Hg). Anti-hypertensive medications were allowed with the exception of alpha-adrenergic blockers, beta-blockers, and clonidine. Medical regimen was to be stable for at least 8 weeks. * Low-density lipoprotein level \<190 mg/dL and triglycerides level \<400 mg/dL. Medications for the treatment of dyslipidemia were allowed as long as the medical regimen had been stable for at least 8 weeks. * No clinically significant abnormality of serum albumin, blood urea nitrogen (BUN), creatinine, bilirubin, calcium and phosphorus * Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) within 2.5 times upper limit of normal (ULN) * No clinically significant abnormality of hematocrit, white blood cell (WBC) count, WBC differential, or platelets * Fasting glucose ≤126 mg/dL and not receiving hypoglycemic agents * No clinically significant abnormality on urinalysis * Thyroid stimulating hormone (TSH) within 1.5 times ULN or normal triiodothyronine (T3), if TSH was below normal limits * Female subjects of childbearing potential had a negative serum pregnancy test * An IDS-SR score \<2 on individual items: 5 (sadness), 6 (irritability), 7 (anxiety/tension), and 18 (suicidality) and an IDS-SR total score \<30 * Female subjects of childbearing potential were non-lactating and agreed to continue to use effective contraception throughout the study and 30 days after discontinuation of study drug * Completed a food diary for 6 of 7 consecutive days during screening * Able to comply with all required study procedures and schedule * Able to speak and read English * Provided written informed consent Exclusion Criteria: * Obesity of known endocrine origin (e.g., untreated hypothyroidism, Cushing's syndrome, established polycystic ovary syndrome) * Serious medical condition (including but not limited to renal or hepatic insufficiency; congestive heart failure, angina pectoris, myocardial infarction, stroke, claudication, or acute limb ischemia; history of malignancy with exception of non-melanoma skin cancer or surgically cured cervical cancer) * Serious psychiatric illness (e.g., lifetime history of bipolar disorder, schizophrenia or other psychosis, bulimia, and anorexia nervosa; current serious personality disorder, e.g., borderline; severe major depressive disorder, recent \[previous 6 months\] suicide attempt or current active suicidal ideation, recent hospitalization due to psychiatric illness) * Response to the bipolar disorder questions that indicated the presence of bipolar disorder. * Required medications for the treatment of a psychiatric disorder (with the exception of short-term insomnia) within the previous 6 months * History of drug or alcohol abuse or dependence within 1 year * Type I or Type II diabetes mellitus * Baseline ECG with a corrected QT (QTc) interval (using Bazett's formula \>450 millisecond (msec) \[males\] and \>470 msec \[females\]) or the presence of any clinically significant cardiac abnormalities, including but not limited to patterns consistent with myocardial ischemia, electrolyte abnormalities, or atrial or ventricular dysrhythmia or significant conduction abnormalities * Received excluded concomitant medications: any psychotropic agents (including antipsychotic, antidepressant, anxiolytic, mood stabilizer or anticonvulsant agents) with the exception of low-dose benzodiazepine or hypnotic agents for the treatment of insomnia; any anorectic or weight loss agents; any over-the-counter dietary supplements with psychoactive, appetite or weight effects; alpha-adrenergic blockers; beta-blockers; clonidine; coumadin; theophylline; cimetidine; oral corticosteroids; topiramate, Depo-Provera®; smoking cessation agents; regular use of opioid or opioid-like analgesics * History of surgical or device (e.g., lap band) intervention for obesity * History of seizures of any etiology, or of predisposition to seizures (e.g., history of cerebrovascular accident, head trauma with \>5 minutes loss of consciousness, concussion symptoms lasting \>15 minutes, brain surgery, skull fracture, subdural hematoma, or febrile seizures) * History of treatment with bupropion or naltrexone within the preceding 12 months * History of hypersensitivity or intolerance to bupropion or naltrexone * Used drugs, herbs, or dietary supplements believed to significantly affect body weight or participated in a weight loss management program within one month prior to baseline * Loss or gained \>4.0 kilograms within the previous 3 months * Females who were pregnant or breast-feeding or planning to become pregnant during the study period or within 30 days of discontinuing study drug * Planned surgical procedure that could impact the conduct of the study * Received any investigational drug or used an experimental device or procedure within the previous 30 days * Participated in any previous clinical trial conducted by Orexigen * Had any condition that in the opinion of the investigator made the subject unsuitable for inclusion into the study