Quetiapine fumarate (Seroquel): a new atypical antipsychotic

The goal of antipsychotic drug development efforts over the past 10 years has been to develop agents with increased efficacy and safety and fewer of the side effects commonly associated with the older antipsychotic medications. The newer agents, often called atypical antipsychotics, are effective in treating both the positive and negative symptoms of schizophrenia and are associated with fewer neurological- and endocrine-related side effects compared to the older agents. As a result, patients are likely to remain on therapy longer, preventing relapses and costly hospitalizations. Quetiapine fumarate (Seroquel) is the most recently introduced atypical antipsychotic and is indicated for the management of the manifestations of psychotic disorders and schizophrenia. Quetiapine, like clozapine (the archetypal atypical antipsychotic), interacts with a broad range of neurotransmitter receptors and has a higher affinity for serotonin (5-HT(2A)) receptors relative to dopamine (D(2)) receptors in the brain. Further, quetiapine's pharmacological effects appear selective for the mesolimbic and mesocortical dopamine systems, which are believed to be the areas of the brain responsible for the therapeutic effects of antipsychotics. In contrast to most standard antipsychotics and some atypical antipsychotics, quetiapine's effects on the nigrostriatal dopamine system, which is responsible for the extrapyramidal (or motor) side effects, are minimal. Quetiapine also has minimal activity on dopamine receptors in the tuberoinfundibular dopamine system, thereby avoiding the problem of hyperprolactinemia, common with the standard antipsychotics and some atypical antipsychotics. Because of these properties, quetiapine is an effective antipsychotic agent with a relatively benign side effect profile. Several large, placebo- and active-controlled, multicenter trials have shown quetiapine to be effective against both positive (e.g., hallucinations, delusions) and negative symptoms (e.g., emotional withdrawal, apathy) and to have benefits in reducing hostility, aggression and affective symptoms. Patients on long-term treatment report high compliance, good satisfaction, increased ability to function and improvements consistent with a better quality of life. Because of quetiapine's excellent tolerability profile, its use is particularly appropriate in patients especially sensitive to adverse effects, e.g., elderly patients with psychotic symptoms and other neurological disorders such as Parkinson's and Alzheimer's disease.