Toxic haloperidol reactions with observation of serum haloperidol concentration in two children

In 2 children who accidentally received haloperidol (0.26 mg/kg in one and 0.10 mg/kg in another) from a prescription error, haloperidol concentrations in serum in both cases and in cerebrospinal fluid in one case were measured with the radioimmunoassay method during the development of the toxic drug reactions. The serum haloperidol concentrations in both cases were far beyond the proposed therapeutic range in children. Our cases are generally compatible with previous findings of others and indicate that the intensity and/or incidence of toxic reactions of haloperidol may be related to plasma concentrations.