Context: Oxidative stress induced lipid peroxidation has been a significant contributing factor for schizophrenia. Older antipsychotics, like haloperidol , were found to increase lipid peroxidation, whereas, the newer atypical antipsychotics, like olanzapine, did not generate free radicals as metabolic end products.
Aims: The interrelationship of the antioxidant vitamins and antioxidant enzymes, and their overall effect on regulation of oxidative stress induced by haloperidol as compared to olanzapine were analyzed in present study.
Setting and design: It was an open randomized cross sectional study that consisted of two groups of fifty schizophrenic patients treated by haloperidol and olanzapine, respectively for at least six months.
Materials and methods: Serum thiobarbituric acid reacting substances (TBARS) was selected as marker of lipid peroxidation, whereas, serum tocopherols, plasma ascorbate and plasma superoxide dismutase (SOD) activity, were selected to assess the antioxidant vitamin and antioxidant enzyme status, respectively. All measurements were done by standard photometric methods.
Statistical analysis used: Statistical analysis was performed to find out the significance for the differences of means between two groups. Bivariate and partial correlation coefficients for assessing the interrelationship between different parameters were done by using statistical package for social sciences (SPSS) software.
Results: Results showed significantly higher serum TBARS and lower antioxidant values in the haloperidol treated patients. Significant positive correlations among the individual antioxidant parameters and significant negative correlation between all of the antioxidant parameters and serum TBARS were found only in haloperidol treated patients. Plasma SOD activity correlated to plasma ascorbate in both groups. Partial correlation results revealed that the serum tocopherol decreased linearly with an increase in serum TBARS significantly in olanzapine treated patients when effect of plasma ascorbate was controlled.
Conclusions: Haloperidol caused more oxidative stress along with a significant reduction of important antioxidant parameters. Plasma ascorbate was found to be the chief antioxidant on which the activity of both plasma SOD and alpha tocopherol were dependent under oxidative stressful conditions.
Keywords: Antipsychotics; oxidative stress; schizophrenia.