The importance of 5-HT1A receptor agonism in antipsychotic drug action: rationale and perspectives.

Serotonin 5-HT1A receptors are attractive targets for the development of improved antipsychotics. Indeed, extensive evidence in rodent models indicates that the activation of these receptors prevents extrapyramidal symptoms (EPS) induced by dopamine D2 receptor blockade, favors dopaminergic neurotransmission in the frontal cortex, has a positive influence on mood, and opposes NMDA receptor antagonist-induced cognitive and social interaction deficits. Therefore, 'third-generation' antipsychotics that combine partial agonism at 5-HT1A receptors with antagonism (or partial agonism) at D2 receptors have been investigated, including aripiprazole, perospirone, lurasidone (Dainippon Sumitomo Pharma Co Ltd), cariprazine (Gedeon Richter Ltd/Forest Laboratories Inc/Mitsubishi Tanabe Pharma Corp), PF-217830 (Pfizer Inc), F-97013-GD, F-15063 and bifeprunox. Such compounds appear to provide therapeutic benefits against a broader range of symptoms of schizophrenia, including negative symptoms and cognitive deficits that are poorly controlled by established antipsychotics. Recently developed compounds are essentially free of EPS liability, and exhibit little or no interaction at sites that are potentially involved in causing side effects such as weight gain, metabolic disorders or autonomic disturbance. These compounds differ in their balance of 5-HT1A/D2 receptor affinity and agonist or antagonist properties; such differences are likely to translate into distinct therapeutic profiles. The balance of 5-HT1A/D2 receptor properties should therefore be considered when selecting compounds as antipsychotic development candidates.