The use of quetiapine in the treatment of major depressive disorder: Evidence from clinical and experimental studies.

Major depressive disorder (MDD) is a highly debilitating condition that is drawing considerable attention due to its high global prevalence and to the fact that treatments are still far from reaching the total number of patients affected. Among available treatment strategies, quetiapine is an important research target, due to antidepressant responses in patients resistant to classical treatments and in animals submitted to protocols that induce depressive-like behaviours. Quetiapine has a broad spectrum of action, within which are many mechanisms that seem to be related to the most effective antidepressant therapeutic responses. In this review, research results related to the pharmacokinetic profile, neurotransmitters, receptors and signalling molecular targets involved in the functional and structural plasticity of key brain regions in MDD are reported and discussed. Moreover, the physiological mechanisms, which are targets of quetiapine and are involved in both MDD and poor therapeutic response, are reported. The main adverse effects observed from therapeutic dosages and overdose are also described. Finally, the main mechanisms underlying the therapeutic response are highlighted.