About one percent of Americans suffer from schizophrenia, which is described by the National Institute of Mental Health as “a chronic, severe, and disabling brain disorder that has affected people throughout history.” New research indicates an effective treatment may be in the pipeline for patients with this disorder. An experimental drug known as cariprazine effectively treated symptoms, including apathy, associated with schizophrenia, said researchers at the European College of Neuropsychopharmacology conference.

Gedeon Richter, headquartered in Budapest, Hungary, is the pharmaceutical company which is developing cariprazine for treating patients with schizophrenia and patients with bipolar I disorder. The company is also investigating how well the drug works when used as a secondary treatment for people with major depression.

Head-to-Head Study of 2 Drugs

Richter describes cariprazine as “an atypical antipsychotic.” The drug binds to the D2 and D3 dopamine receptors, with a preference for D3. Many neurological processes, including pleasure, memory, motivation, learning, and fine motor control, involve dopamine receptors which are part of our central nervous system. Researchers say quite a few mental illnesses involve abnormal functioning of these receptors, and so drugs developed to treat these disorders often “target” them. Most antipsychotics, for instance, attempt to correct a poorly functioning D2 receptor.

The main symptoms of schizophrenia fall into three categories. Positive symptoms include delusions and hallucinations; negative symptoms include lack of drive and apathy; and cognitive symptoms include problems with attention and memory. Antipsychotics effectively treat the positive symptoms of schizophrenia, but these treatments do not help with negative and cognitive symptoms.

For the current study (originally announced earlier this year), 461 schizophrenia patients from around the world were randomly placed into two groups. They received either risperidone, an antipsychotic commonly used to treat schizophrenia, or the experimental drug cariprazine. During the 26-week study, patients took cariprazine alone, without any additional drugs.

What did the researchers discover? Cariprazine was significantly more effective in treating the negative symptoms of patients with schizophrenia than risperidone. Patients also reported few side effects. In fact, the most common side effects, insomnia and headache (each experienced by about 10 percent of patients), were caused by risperidone and not the experimental drug.

"The current results suggest that D3-dopaminergic mechanisms may play a role in both causing and treating emotional flatness, which deserve further confirmation," Dr. Andreas Meyer-Lindenberg, a professor and chair of psychiatry and psychotherapy at University of Heidelberg, Germany, commented in a press release.

Cariprazine already has been studied in safety and efficacy tests involving more than 2,700 patients, according to Richter. This Eastern European company is developing the drug with the assistance of North American and Asian companies.

Source: Debelle M, Nemeth G, Szalai E, et al. Cariprazine as monotherapy for the treatment of schizophrenia patients with predominant negative symptoms: a double-blind, active controlled trial. Presentation the ECNP Conference. 2015.