Relação entre a indução ao ganho de peso decorrente do uso crônico de olanzapina e os SNPs TaqIA no gene DRD2 e G-308A no gene TNF-α

Abstract

Olanzapine is a second generation antipsychotic that show low incidence of extrapyramidal side effects and has been recommended as the first line drug for the treatment of schizophrenia and is also used in the treatment of bipolar disorder. But it has the weight gain as a side effect which is common in the chronic use of this medicine. A comprehensive review of the literature revealed that olanzapine induces more weight gain than most other antipsychotics, except clozapine. The incidence of weight gain induced by olanzapine and associated diseases such as diabetes and cardiovascular diseases is higher in this group of patients than in the general population. These unwanted side effects have decreased patients' adherence to treatment. Many clinical observations and studies have attempted to elucidate the possible mechanism involved. However, to date, the mechanism underlying the weight gain induced by olanzapine remains unclear. This present study retrospective evaluates 21 patients using olanzapine for a period of 20 to 119 months, compared within the sample, patients who lost weight or remained stable (<7% gain in relation to BMI) group which gained weight at a moderate or severe way during the use of olanzapine (> 7% gain in relation to BMI). We also evaluated the levels of glucose and plasma lipids of all patients. For the group of patients were also analyzed genetic polymorphisms of TaqIA DRD2 gene and G-308A TNF-α gene by PCR-RFL and ARMS-PCR, respectively. TaqIA of genetic polymorphism (C32806T) in the DRD2 gene was correlated with prolonged use of olanzapine with relevant statistical significance in relation to weight gain and biochemical changes observed in plasma of patients. Regarding the genetic variants of the SNP G-308A TNF-α gene, the findings of this study failed to corroborate or refute the findings of other studies.