The chemical interaction between the neurotransmitter dopamine and the antipsychotic drugs olanzapine and quetiapine

Mental disorders like schizophrenia affect about 0.7% of the world population. Nowadays, the treatment consists of atypical antipsychotic drugs, mainly olanzapine and quetiapine. In this paper, we observed the chemical interaction between both olanzapine and quetiapine, antipsychotic drugs, with dopamine in phosphate buffer solutions at physiological pH using cyclic and differential voltammetry techniques, UV-Vis and EPR spectra. A solution containing both antipsychotic drugs and dopamine resulted in a shift of dopamine's redox processes, hindering its electrochemical oxidation. The chemical interaction was voltametrically investigated and a mechanism is proposed. In addition, it was observed that the reactions of both drugs with DA are first-order, presenting kinetic rate constants of 1.5 10(-2) s(-1) and 9.0 10(-3) s(-1) for olanzapine and quetiapine, respectively, at pH=7.4. To further evaluate the chemical reaction, aminimalist model between PIPES molecule and catechol was proposed and tested. The model presented a similar signal decrease and kinetic rate constant to those observed for both olanzapine and quetiapine reaction with dopamine, reinforcing the data obtained which strongly suggests that the chemical reaction occurs between piperazine and catechol moieties.

Automated summary

This study observed the chemical interaction between olanzapine and quetiapine, antipsychotic drugs, with dopamine in phosphate buffer solutions at physiological pH. The reactions of both drugs with dopamine were found to be first-order, with proposed mechanism suggesting a chemical reaction occurs between piperazine and catechol moieties.