Lonasen (Generic name: blonanserin) is a new anti-psychotic agent that was approved for manufacturing/sales in January 2008. It is primarily employed to treat schizophrenia.
Schizophrenia is a psychiatric disorder. Latent schizophrenia is present in approximately 0.8% of the population. The number of patients with this disorder is estimated to be 700,000 in Japan and 2,200,000 or more in the United States. The mesolimbic system and midbrain-cortex dopamine nerves may be associated with the onset of schizophrenia. Various psychiatric symptoms, including positive symptoms such as hallucination/delusion, negative symptoms such as flat emotions/diminished thinking/loss and reduction of volition, and cognitive impairment such as reduced attentiveness/disturbance of the information-processing capacity, appear.
An anti-psychotic agent first introduced for the treatment of schizophrenia, chlorpromazine, was identified as a compound with tranquilizing actions. In Japan, this agent became commercially available in 1955. It is classified as a first-generation anti-psychotic agent, which primarily reduces positive symptoms by blocking the dopamine D2 receptors of the central nerves (D2 receptors).
Since the appearance of this agent, schizophrenia treatment has markedly advanced. Subsequently, many first-generation anti-psychotic agents were developed. These agents were effective for positive symptoms, but their effects on negative symptoms were not marked. In addition, side effects such as extrapyramidal symptoms (akathisia, tremor), oversedation, and a decrease in the blood pressure were observed, raising important issues regarding clinical application.
In the 1980's, the relationship between serotonin 5-HT2 receptors in the central nervous system (CNS) and the effects on negative symptoms/appearance of extrapyramidal symptoms was clarified. Second-generation anti-psychotic agents that relieve negative symptoms without causing side effects such as extrapyramidal symptoms have been positively developed. In Japan, since the first second-generation anti-psychotic agent became commercially available in 1996, drug therapy for schizophrenia has markedly changed from combination/high-dose therapy to monotherapy with second-generation anti-psychotic agents.