Quetiapine, Olanzapine and Haloperidol Affect Human Plasma Lipid Peroxidation in vitro

Objective: Oxidative injury in schizophrenia may be caused not only by pathophysiological processes but partly also by treatment with antipsychotics. The purpose of the present study was to examine and to compare the effects of quetiapine (QUE), olanzapine (OLA) and haloperidol (HAL), at final concentrations corresponding to doses used for treatment of acute episodes of schizophrenia, on plasma lipid peroxidation in vitro, measured by the level of thiobarbituric acid-reactive substances (TBARS). Methods: Blood from 30 healthy volunteers was collected into ACD (citric acid/citrate/ dextrose) solution. The drugs in form of active substances were dissolved in 0.01% dimethyl sulfoxide, added to plasma at the final concentrations [QUE (175 and 275 ng/ml), OLA (20 and 40 ng/ml), HAL (4 and 20 ng/ml)] and incubated for 1 and 24 h at 37 ° C. The level of TBARS was measured spectrophotometrically (according to the Rice-Evans method, 1991). Results: The comparative study in vitro showed that QUE causes a decrease in the TBARS level in plasma, whereas HAL increases the plasma TBARS level. After 24 h of incubation of plasma with QUE or HAL (at lower and higher concentrations), the differences in TBARS levels between the drugs were significant (p = 5.9 ! 10 –4 , p = 2.2 ! 10 –5 , respectively). Received: May 1, 2009 Accepted after revision: September 27, 2010 Published online: March 22, 2011 Anna Dietrich-Muszalska, MD, PhD Department of Affective and Psychotic Disorders Medical University of Lodz, Czechoslowacka 8/10 PL–92-216 Lodz (Poland) Tel. +48 42 691 881 787, Fax +48 42 675 7403, E-Mail tzn_lodz @ post.pl © 2011 S. Karger AG, Basel 0302–282X/11/0634–0197$38.00/0 Accessible online at: www.karger.com/nps Dietrich-Muszalska /Kontek / Rabe-Jabłońska Neuropsychobiology 2011;63:197–201 198 The second-generation antipsychotics (SGAs) may also have some effects on oxidative stress, measured by the level of lipid peroxidation in plasma. The effects of olanzapine (OLA) and quetiapine (QUE) on this process are explained only partially. QUE and OLA belong to the chemical class of benzisoxazole derivatives and have been found to be effective in the treatment of schizophrenic disorders, with therapeutic activity mediated through a combination of D2 and 5HT2 receptor antagonism [8] . Moreover, it has been shown that they have a very low potential for causing extrapyramidal symptoms (EPS) across the full dose range [9, 10] . QUE and OLA may improve cognitive functions (attentional, motor, and visuomotor skills) as well as executive functions connected to the psychopathology of schizophrenia [10] . It seems that the antioxidant mechanism of QUE and OLA may contribute to the low incidence of EPS and movement disorders caused by these drugs in patients with schizophrenia, and may be effective in the treatment of TD caused by other antipsychotics [10, 11] . The aim of the study was to evaluate the effects of SGAs and establish whether there is a difference among OLA, QUE and HAL action regarding their influence on lipid peroxidation in human plasma, measured by the level of thiobarbituric acid-reactive substances (TBARS). Materials and Methods Inclusion Criteria of Healthy Subjects Blood samples were taken from 30 healthy males aged between 25 and 29 years (average: 28.3, SD = 1.5 years), without psychiatric, neurological or somatic disorders or a history of head injuries, lipid or carbohydrate metabolism disorders, with a normal body mass index, and not being treated with any drugs. Healthy subjects (no smokers) did not use any addictive substances and antioxidant supplementation, and their diet was balanced (meat and vegetables). They lived in similar socioeconomic conditions. Psychiatric examination (using the M.I.N.I. – Mini International Neuropsychiatric Interview [12] ), and neurological and somatic examinations were performed. All subjects signed a consent to the participation in the study, according to the protocol accepted by the Committee for Research on Human Subjects of the Medical University of Lodz (No. RNN/899/2000). Isolation of Plasma Human blood (3 ! 7.5 ml) was collected into ACD solution (citric acid/citrate/dextrose; 5: 1 v/v) between 8.00 and 8.30 a.m. and centrifuged for 20 min at 2,500 rpm and 20 ° C in a Sigma 3K30 centrifuge to obtain plasma. The drugs obtained from the manufacturers (QUE: Celon Pharma, Poland; OLA: Adamed, Poland; HAL: Polfa-Warsaw, Poland) in the form of active ingredients were dissolved in 0.01% dimethyl sulfoxide (Sigma). Drug solutions were added to 0.5 ml of plasma (QUE at the final concentrations of 175 and 275 ng/ml; OLA 20 and 40 ng/ml; HAL 4 and 20 ng/ml) and incubated for 1 and 24 h at 37 ° C. The controls were plasma samples containing 0.01% dimethyl sulfoxide without drug. Metabolites of QUE and OLA were not investigated. Evaluation of Lipid Peroxidation Level In control samples and samples of plasma after the incubation with the drug, the concentrations of TBARS were measured spectrophotometrically, according to the Rice-Evans method [13] . The absorbance was measured in a SEMCO spectrophotometer at 535 nm in 1-cm cuvettes. The TBARS expressed in micromoles per liter were calculated based on the absorbance value, using the molar extinction coefficient for TBARS ( = 1.56 ! 10 5 M –1 ! cm –1 ). All estimations were performed twice, including control plasma samples, in which spontaneous lipid peroxidation, without the influence of the drug, was measured. Statistical Analysis The results were subjected to statistical analysis (mean values and standard error of the mean). The significance of differences in TBARS levels (drug-treated samples vs. control) was calculated using the paired Student’s t test. The two-way ANOVA test was used. Post hoc comparisons for the TBARS levels were carried out with the NIR test. Statistica v. 6.0 by Statsoft, Inc. was used.