Lipid status, anti-oxidant enzyme defence and haemoglobin content in the blood of long-term clozapine-treated schizophrenic patients

ObjectiveDespite clozapine's unique effectiveness in patients with schizophrenia, a number of adverse effects have been recognised including abnormalities in lipid and glucose metabolisms. A high clozapine level in red blood cells (RBCs) and disturbed anti-oxidant enzyme activities in blood from schizophrenic patients prompted us to investigate lipid status and anti-oxidant enzyme defence in the blood of chronic schizophrenic patients on long-term clozapine therapy.MethodsPlasma lipids, RBC anti-oxidant enzyme activities and haemoglobin (Hb) content were measured using established procedures in a group of eighteen chronically-medicated (average 630 days of therapy) schizophrenic patients receiving clozapine (average dose of 295 mg/day) and data were compared with those from a group of eighteen well-matched normal controls.ResultsSignificantly higher levels of plasma triglycerides (by 47%, p < 0.01) and total cholesterol and phospholipids (by 8% and 11%, respectively p < 0.05) in patients were found. CuZn-superoxide dismutase (SOD1) activity was markedly higher (by 35%, p < 0.001) while selenium-dependent glutathione peroxidase (GSH-Px1) activity was markedly lower (by 41%, p < 0.001) in patients. In addition, metHb and HbA1c levels in patients were significantly higher (by 58% and 25%, respectively p < 0.001). SOD1 activity was negatively correlated (p < 0.001) to GSH-Px1 activity in patients.ConclusionsThe findings support the view that ongoing oxidative stress may be a mechanism by which clozapine induces some adverse effects that increase the risk of diabetes and metabolic syndrome. If valid, this would indicate that in parallel with long-term clozapine treatment, schizophrenic patients could be encouraged to make some lifestyle changes to limit the detrimental effects of the medication.