Study of Fluoxetine in Adults With Autistic Disorder

Inclusion criteria: * Meets DSM-IV and ADI criteria for autistic disorder * Patients must use effective contraception * Negative pregnancy test * Clinical Global Impression-Severity Scale for Autistic Disorder (CGI-AD) score of 4 Exclusion criteria: * Pregnant or nursing * Prior or concurrent history of mental disorders, including schizophrenia, schizoaffective disorder, organic mental disorders, or bipolar disorders * Concurrent depression determined by DSM-IV diagnosis * Serious suicidal risk * Active seizure disorder within the past 2 years * Clinically significant or unstable medical illness, including hematopoietic or cardiovascular disease * Any organic or systemic disease * Any geographical condition that would preclude study compliance * Prior or concurrent gastrointestinal, liver, or kidney disease * Any other concurrent condition that interferes with the absorption, distribution, metabolism, or excretion of drugs * Prior or concurrent cerebrovascular disease or brain trauma * Prior or concurrent clinically significant unstable endocrine disorder, such as hypo- or hyperthyroidism * Prior or concurrent malignancy * Clinically significant abnormalities on EKG, laboratory tests, or physical exam * Requirement for ECT or any other psychotropic medication * Inability to tolerate taper from psychoactive medication * History of hypersensitivity or severe side effects associated with the use of fluoxitine or other serotonin reuptake inhibitors * Treatment with any drug known to have a well-defined potential for toxicity to a major organ within the past 30 days * Concurrent terfenadine (Seldane) or astemizole (Hismanal) * Prior treatment with fluoxetine of 40 mg/day for 6 weeks * Prior electroconvulsive therapy within the past 3 months * Prior investigational drug use within the past 30 days * Prior Monoamine oxidase inhibitor use within the past 14 days * Prior long-acting phenothiazines within the past 6 weeks * Prior psychotropic drugs within the past 7 days * Prior fluoxetine within the past 6 weeks * Requirement for any therapeutic intervention that would confound study evaluation