United Kingdom. A new antipsychotic agent for the treatment of schizophrenia, quetiapine (SerquelR: Zeneca) has been approved.

Quetiapine is one of a group of drugs known as "atypical" antipsychotics. Clozapine was the first atypical antipsychotic drug to be approved, followed by risperidone, olanzapine and sertindole.

Quetiapine interacts with a broad range of receptors in the brain. It is an antagonist at serotonin (5HT2) and dopamine D1 and D2 receptors. It exhibits a higher affinity for serotonin receptors than for dopamine receptors and also possesses antihistamine and alfa-adrenergic antagonist properties, but has little effect on muscarinic receptors.

Studies have shown that the incidence of extrapyramidal effects is no different from placebo across the full dose range. There is no requirement for blood monitoring with quetiapine. The drug does not cause prolactin levels to rise (an effect associated with risperidone). A rise in prolactin can contribute to sexual dysfunction, impotence, lactation, breast pain and breast enlargement. Unlike sertindole, quetiapine does not affect cardiac conduction.

Reference: The Pharmaceutical Journal 259: 504 (1997).