There was a clear difference between the groups. This finding is based on data of moderate quality. In a 2013 comparison of 15 antipsychotics in effectiveness in treating schizophrenia, quetiapine demonstrated standard effectiveness. Quetiapine Drug Class Quetiapine (Seroquel) is an atypical antipsychotic, specifically a dibenzothiazepine derivative. 1 Quetiapine is used alone or together with other medicines to treat bipolar disorder (depressive and manic episodes) and schizophrenia. Quetiapine extended-release tablet is also used together with other antidepressants to treat major depressive disorder. Seroquel (quetiapine) is not classified as a controlled substance under the U.S. Controlled Substances Act, but it is a prescription-only antipsychotic with known risks of side effects, misuse, and withdrawal if stopped abruptly. Seroquel tablets may be used as part of a treatment program to treat bipolar disorder and schizophrenia in children and teenagers. Quetiapine belongs to class of medications called atypical antipsychotics. It works by changing the activity of certain natural substances in the brain. CRIPTION SEROQUEL® (quetiapine fumarate) is a psychotropic agent belonging to a chemical class, the dibenzothiazepine der. atives. The chemical designation is 2-[2-(4-dibenzo [b,f]. Quetiapine is commonly used for the following mood conditions. Quetiapine may also be used for other conditions as determined by your healthcare provider. How does quetiapine work (mechanism of. Seroquel belongs to a class of drugs called Antipsychotics, 2nd Generation; Antimanic Agents. It is not known if Seroquel is safe and effective in children younger than 12 years of age. The FDA drug label explicitly states that SEROQUEL® (quetiapine) is an atypical antipsychotic belonging to a chemical class, the dibenzothiazepine derivatives 1. Seroquel belongs to a class called second-generation (atypical) antipsychotics. It is FDA-approved to treat schizophrenia, manic episodes in bipolar I disorder, depressive episodes in bipolar disorder, and long-term maintenance of bipolar I disorder.