This is a randomized (the drug is assigned by chance), 8-week, double-blind (neither physician nor patient knows the treatment that the patient receives), placebo-controlled (placebo is an inactive substance that is compared with a drug to test whether the drug has a real effect in a clinical trial), parallel-group (each group of patients will be treated at the same time), flexible-dose, multicenter study. It will be followed by a 48-week, flexible-dose, open-label (all people know the identity of the intervention) extension, to evaluate the efficacy and safety of risperidone in children and adolescents with a diagnosis of autistic disorder (severe form of pervasive developmental disorder) who have associated irritability. The study consists of up to 2-week screening phase, an 8-week double-blind phase, a 48-week open-label phase, and a 1-week follow-up phase.
The purpose of this study is to evaluate the efficacy of risperidone compared with placebo in children and adolescents with irritability associated with autistic disorder.