Anxiety in Recovering Opiate Dependence

Inclusion Criteria: * Provision of written informed consent * A diagnosis of opiate dependence as defined by Diagnostic and Statistical Manual of Mental Disorders- Fourth Edition (DSM-IV) during the past two years. * A diagnosis of generalized anxiety disorder as defined by Diagnostic and Statistical Manual of Mental Disorders- Fourth Edition (DSM-IV) within the past 6 months. * Males and females aged 21-55 years * Female patients of childbearing potential must be using a reliable method of contraception and have a negative urine human chorionic gonadotropin (HCG) test at enrollment * Able to understand and comply with the requirements of the study * Subjects must be free of illicit drug use for the past 3 months * Subjects must have received methadone maintenance therapy for at least 3 months, and have been at least 2 weeks methadone-free * Good health, as assessed by medical history, physical examination and laboratory tests Exclusion Criteria: * Pregnancy or lactation * Current diagnosis of any Axis I disorder other than GAD, substance dependence in remission, or nicotine dependence * Patients who, in the opinion of the investigator, pose an imminent risk of suicide or a danger to self or others * Known intolerance or lack of response to quetiapine fumarate, as judged by the investigator * Use of any of the following cytochrome P450 3A4 inhibitors in the 14 days preceding enrolment including but not limited to: ketoconazole, itraconazole, fluconazole, erythromycin, clarithromycin, troleandomycin, indinavir, nelfinavir, ritonavir, fluvoxamine and saquinavir * Use of any of the following cytochrome P450 inducers in the 14 days preceding enrollment including but not limited to: phenytoin, carbamazepine, barbiturates, rifampin, St. John's Wort, and glucocorticoids * Administration of a depot antipsychotic injection within one dosing interval (for the depot) before randomisation * Medical conditions that would affect absorption, distribution, metabolism, or excretion of study treatment * Unstable or inadequately treated medical illness (e.g. diabetes, angina pectoris, hypertension) as judged by the investigator * Involvement in the planning and conduct of the study * Previous enrollment or randomisation of treatment in the present study. * Participation in another drug trial within 4 weeks prior enrollment into this study or longer in accordance with local requirements * A patient with Diabetes Mellitus (DM) fulfilling one of the following criteria: * Unstable DM defined as enrollment glycosylated hemoglobin (HbA1c) \>8.5%. * Admitted to hospital for treatment of DM or DM related illness in past 12 weeks. * Not under physician care for DM * Physician responsible for patient's DM care has not indicated that patient's DM is controlled. * Physician responsible for patient's DM care has not approved patient's participation in the study * Has not been on the same dose of oral hypoglycaemic drug(s) and/or diet for the 4 weeks prior to randomization. For thiazolidinediones (glitazones) this period should not be less than 8 weeks. * Taking insulin whose daily dose on one occasion in the past 4 weeks has been more than 10% above or below their mean dose in the preceding 4 weeks Note: If a diabetic patient meets one of these criteria, the patient is to be excluded even if the treating physician believes that the patient is stable and can participate in the study. * An absolute neutrophil count (ANC) of 1.5 x 109 per liter * Positive urine drug screening test for drugs of abuse