Quetiapine sulfoxide dihydrochloride (Quetiapine S-oxide dihydrochloride) is a main metabolite of Quetiapinem. Quetiapine is a second-generation antipsychotic^[1]. Quetiapine is a 5-HT receptors agonist and a dopamine receptor antagonist^[2]. In Vivo: The C_max value (mean±SD) is estimated for Quetiapine sulfoxide (77.3±32.4 ng/mL). The AUC_last value is estimated for Quetiapine sulfoxide (1,286±458 ng•h/mL). For Quetiapine sulfoxide, metabolic ratio decreases with time, from 119% on average 2 hours after dosing to 30% on average 72 hours after dosing^[1].