Haloperidol and reduced haloperidol concentrations and psychiatric ratings in schizophrenic patients treated with...

Recent reports have suggested an augmentation by ascorbic acid of haloperidol treatment of schizophrenic patients. This study was designed to examine whether pharmacokinetic interactions between ascorbic acid and haloperidol occur in this population. Eight male inpatients diagnosed as having chronic schizophrenia by DSM-III-R criteria and stabilized on a fixed dose of haloperidol were given oral doses of ascorbic acid, 4.5 grams daily, for 2 weeks in an open trial. Serum concentrations of haloperidol and is metabolite, reduced haloperidol, were measured by high performance liquid chromatography. Psychiatric symptoms were monitored using the Psychiatric Symptom Assessment Scale performed by nursing staff blind to the haloperidol status but not to the ascorbic acid dosage. The addition of ascorbic acid was not associated with any change in psychopathology in this group of patients, nor was there any apparent pharmacokinetic interaction with haloperidol.