Serum Haloperidol Levels in Older Psychotic Patients

The authors measured serum levels of haloperidol (HL) in outpatients ages 45-83 years with psychosis treated with HL for at least 1 month. Blood was collected from 32 patients with either schizophrenia (n = 23) or Alzheimer's disease (AD) (n = 9). HL daily dose was greater in patients with schizophrenia (median age, 59) than in AD patients (median age, 80) (P < 0.0005), but no significant group differences in HL serum concentrations were observed. In the total sample, age correlated negatively with HL dose (P < 0.001) and positively with the ratio of serum HL level/dose (P < 0.05). The ratio of HL level/dose was higher in the elderly AD patients than in younger subjects with schizophrenia (P < 0.005). Serum HL levels were much lower than those reported in younger schizophrenia patients, but comparable to those reported in elderly patients with AD. Aging-related and disease-associated pharmacokinetic and pharmacodynamic changes may reduce the need for higher neuroleptic doses as well as higher blood levels in older patients.