Cardiovascular and other physical effects of acute administration of naltrexone in autistic children.

ABSTRACT The physical side effects of acutely administered naltrexone (0.5, 1.0, 1.5, and 2.0 mg/kg, orally) were compared with placebo in 13 children (3-12 years old) with autism. Heart rate, systolic blood pressure, mean arterial blood pressure, and axillary body temperature were obtained before and 1 h after placebo or drug administration. Serum concentrations of the liver enzymes glutamic-oxaloacetic transaminase (SGOT) and glutamic-pyruvic transaminase (SGPT) were obtained 1 h and 24 h after drug. In comparison with placebo, no significant effects of any of the four doses of naltrexone were found on any of these measures. Three hours after administration, there were no significant effects of acute naltrexone on EKG parameters (heart rate, axis, PR, QRS, QT, or QTc) compared to predrug values. These data support the safety of acute administration of naltrexone on vital signs, EKG, and liver function in preadolescent children with autism and are consistent with studies in healthy normotensive adults. In view of prior findings that naltrexone can alter cardiovascular function in certain pathologic states (including some that involve increased opioid peptide activity) and findings of increased opioid activity in some autistic individuals, the absence of cardiovascular effects of naltrexone in autistic children is tentatively suggestive of the safety of acutely administered naltrexone. Since chronic high doses of naltrexone can increase liver transaminase levels in adults, it remains advisable for clinicians to monitor liver function in children receiving chronic naltrexone treatment. Other adverse effects of acute naltrexone in these children appeared to be minimal.