Risperidone monotherapy in preschool children with pervasive developmental disorders.

The aim of this preliminary study was to examine the short-term efficacy and safety of the atypical antipsychotic risperidone in preschool autistic children. The sample consisted of 10 subjects (7 males and 3 females) aged 3 9/12 to 6 6/12 years (mean age 4.7 years). A 16-week open-label trial with risperidone monotherapy was initiated at a starting dose of 0.25 mg daily and was increased to a maximum dose of 0.50 mg (0.027 mg/kg daily). Outcome measures were the Childhood Autism Rating Scale, the Children's Psychiatric Rating Scale, Clinical Global Impression (improvement score), and the Children's Global Assessment of Functioning. Two subjects did not complete the trial because of side effects (tachycardia and flushes, fever and hyporexia). After the 16-week treatment, data from the eight children who completed the trial indicated a modest improvement in the Childhood Autism Rating Scale total score, Children's Psychiatric Rating Scale total score, and Children's Global Assessment of Functioning. According to the Clinical Global Impression, the global improvement score for four subjects was much improved or very much improved; the score for the other four children was minimally improved. None of the children exhibited behavioral deterioration. The side effects in the eight children were not severe.