The effects of acute, orally administered naltrexone (0.5, 1.0, 1.5 and 2.0
mg/kg), a potent opiate receptor antagonist, on auscultated heart rate, systolic blood pressure
and axillary body temperature were investigated before and about 1 h postdrug in 5 autistic
children (4-12 years of age). In addition, an electrocardiogram was recorded on each child
before and about 3 h after placebo or 2.0 mg/kg of naltrexone. Finally, the serum concentrations
of the liver enzymes glutamic-oxaloacetic transaminase (SGOT) and glutamic-pyruvic
transaminase (SGPT) were measured 24 h following placebo or naltrexone administration.
Naltrexone had no statistically significant effects on any of these measures in comparison
with baseline or placebo levels. Thus, these data provide preliminary evidence for the safety
of acute administration of naltrexone in children.