The purpose of this trial was to investigate the short-term safety and efficacy of quetiapine fumarate in the treatment of children and adolescents with autistic disorder (AD).

This was a 16-week, open-label trial that included 6 male subjects with a mean age of 10.9 ± 3.3 years. All subjects met the DSM-IV criteria for AD and functioned in the mentally retarded range (mild, n = 2; moderate, n = 3; severe, n = 1). Behavioral ratings were obtained at baseline and every four weeks thereafter.

Overall, there was no statistically significant improvement between baseline and endpoint for the group as a whole. Only two subjects completed 16 weeks of treatment and were considered "responders" by the global improvement item of the Clinical Global Impression Scale (CGIS). Dosages ranged from 100 to 350 mg/day (1.6–5.2 mg/kg/day). Subjects dropped out prematurely because of lack of response and sedation, limiting further dose increases (n = 3), and because of a possible seizure during the fourth week of treatment (n = 1). Other significant side effects included behavioral activation, increased appetite and weight gain (range, 0.9 to 8.2 kg).

Quetiapine was poorly tolerated and associated with serious side effects in this clinical population.