Blood lactate levels as a biomarker of antipsychotic side effects in patients with schizophrenia

Background: Antipsychotic drugs (APs) are widely prescribed in psychiatry primarily for the treatment of psychosis in schizophrenia and bipolar disorders. An issue related to poor prognosis in patients with chronic illness relates to the accumulation of lactate levels in blood, leading to patients that become critically ill. It is suggested that haloperidol and olanzapine, as common therapy for schizophrenia, are associated with increased levels of blood lactate, which may contribute towards the extra-pyramidal side effects. Aims and method: In this study, 88 patients attending the psychiatry outpatient clinic of Mansoura University Hospital, under treatment with typical APs (chlorpromazine or haloperidol) or the atypical APs (risperidone, olanzapine or quetiapine) were followed over a three-month period. Blood lactate levels were assessed at diagnosis, ten days and 90 days after the start of AP treatment. Extra-pyramidal symptoms (EPSs) were studied in participants during the course of this study. Results: Chlorpromazine and haloperidol caused significant increases in lactate levels within the first ten days of therapy, while after 90 days, all APs showed significant increases in arterial blood lactate levels in comparison with the first baseline measurement (for all APs, p-values <0.0001). Dystonia was reported by patients on chlorpromazine, haloperidol and risperidone therapies, while Parkinsonian-like manifestations were reported with all APs tested except for quetiapine. Both dystonia and Parkinsonian-like manifestations were also observed alongside the significant increases in arterial blood lactate levels in comparison to patients on therapy not displaying EPSs. Conclusion: These findings suggest elevated blood lactate levels may serve as early biomarkers for occurrence of extra-pyramidal symptoms in patients on chronic APs treatment.