Ritanserin is a serotonin antagonist

Serotonin antagonist

A serotonin antagonist is a drug used to inhibit the action at serotonin receptors.Many of the most important medications of this class selectively act at the 5-HT3 receptor, and thus are known as 5-HT3 antagonists...

 with possibilities for the treatment of many neurological disorders.

When used together with typical antipsychotics in the treatment of schizophrenia

Schizophrenia

Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...

 is able to decrease negative symptoms and adds some "atypicality" as parkinsonism

Parkinsonism

Parkinsonism is a neurological syndrome characterized by tremor, hypokinesia, rigidity, and postural instability. The underlying causes of parkinsonism are numerous, and diagnosis can be complex...

 is slightly decreased.

Pharmacology

Ritanserin acts as a 5-HT_2A

5-HT2A receptor

The mammalian 5-HT2A receptor is a subtype of the 5-HT2 receptor that belongs to the serotonin receptor family and is a G protein-coupled receptor . This is the main excitatory receptor subtype among the GPCRs for serotonin , although 5-HT2A may also have an inhibitory effect on certain areas such...

 and 5-HT_2C receptor

5-HT2C receptor

The 5-HT2C receptor is a subtype of 5-HT receptor that binds the endogenous neurotransmitter serotonin . It is a G protein-coupled receptor that is coupled to Gq/G11 and mediates excitatory neurotransmission. HTR2C denotes the human gene encoding for the receptor, that in humans is located at the...

 antagonist

Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...

, with higher affinity for the former site.