The main justification for the development of extended release quetiapine is that it can be given once daily. This contrasts with the recommended regimen for the immediate release form of quetiapine, which is usually twice daily.
Quetiapine (Seroquel) is an atypical antipsychotic for the treatment of schizophrenia that has also recently established a role in the treatment of bipolar disorder for both mania and depression. It is a sedative antipsychotic agent, which in clinical practice now occupies the role that was previously held by the conventional antipsychotic chlorpromazine. In contrast to chlorpromazine, quetiapine is unlikely to cause extrapyramidal side effects (e.g. dystonic reactions, parkinsonism, akathisia and tardive dyskinesia) or hyperprolactinaemia. Similar to chlorpromazine, quetiapine may cause anticholinergic side effects and postural hypotension (although usually to a lesser degree than chlorpromazine).