Safety Study of Memantine in Pediatric Patients With Autism, Asperger's Disorder or Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS)

This clinical study was a 48-week, multicenter, multinational, open-label extension study in pediatric outpatients with autism, Asperger's Disorder, or PDD-NOS conducted at 106 study centers. Patients were eligible for this long-term extension study if they had: * completed the open-label Study MEM MD 67,or * completed the open-label Study MEM-MD-91, or * completed the double-blind Study MEM-MD-68, or * discontinued study MEM-MD-68 by meeting requirements for loss of therapeutic response The weight-based dose limits in this study were as follows: Group A: ≥ 60 kg; maximum 15 mg/day Group B: 40-59 kg; maximum 9 mg/day Group C: 20-39 kg; maximum 6 mg/day Group D: \< 20 kg; maximum 3 mg/day The decision to close the study early was based on data from 2 double-blind placebo-controlled studies (MEM-MD-57A and MEM-MD-68) that failed to demonstrate a statistically significant difference between memantine and placebo in the primary efficacy parameter based on Social Responsiveness Scale (SRS) total raw score.