The most frequent targets for pharmacologic intervention in PDD patients include associated comorbid conditions: hyperactivity, inattention, compulsive-like behaviors, anxiety, depression, aggression, self-injurious behavior, repetitive or stereotypic behaviors, and sleep disturbances [1-2].

To compare efficacy and tolerability of risperidone and atomoxetine in the treatment of severe and challenging behaviors in children with PDD.

Was conducted 8-week double-blind, placebo-controlled study with parallel group of comparison and flexible doses of Risperidon (1.0-3.0 mg; MD = 1,8) and Atomoxetine (25.0 – 40.0 mg; MD = 32,8). Were randomized 80 children from 12 to 18 years old (MD = 10,8) with the assessment ≥ 6 points on the diagnostic criteria for DSM IV-TR for autism, ≥12 balls Irritability by ABC-C. All children were assessed by an additional ADI-R, ADOS. Drug efficacy was assessed weekly using the ABC-C, CGI-I / CGI-S, Adverse event recording.

Risperidone and Atomoxetine are more effective than placebo in Irritability, Agitation, Crying subscales (F = 2,30, DF = 1,47, P = 0,12), Hyperactivity, Noncompliance (F = 103,24, DF = 1,68, ? ≤ 0,0001), Lethargy, Social Withdrawal (F = 2,30, DF = 1,47, P = 0,12), Stereotypic Behavior (F = 27,94, DF = 1,24, ? ≤ 0,0001). In Risperidone therapy was observed Inappropriate Speech retardation, and more frequently extra pyramidal side effects.

Risperidon (1.0-3.0 mg / day) and Atomoxetine (25.0 – 40.0 mg / day) are more effective than placebo and well-tolerated and can be recommended for treatment of severe and challenging behaviors in children with PDD.