The US Food and Drug Administration (FDA) has approved the first and only antipsychotic treatment for schizoaffective disorder, a common debilitating mood disorder that is difficult to distinguish from schizophrenia.

Invega (paliperidone), marketed by Janssen, a division of Ortho-McNeil-Janssen Pharmaceuticals, has now been approved as extended-release tablets used either as a monotherapy or as adjunctive therapy to mood stabilisers and/or antidepressants.

Patients with schizoaffective disorder experience the same hallucinations or delusions as schizophrenia patients as well as the symptoms of mania and/or depression.

Schizoaffective disorder is thought to account for approximately 24% of cases of mental health services patients in the US.

SUNY Downstate Medical Center spokesperson Nina Schooler said that schizoaffective disorder can be challenging to diagnose because of the broad range of symptoms patients experience.

“The approval of Invega is exciting as it is the only antipsychotic treatment proven to be efficacious with a demonstrated tolerable safety profile treating the psychotic and affective symptoms present in this understudied population,” Schooler said.

Approval for the new drug was based on two international, randomised, double-blind, placebo-controlled studies of patients with an established diagnosis of schizoaffective disorder. The first study involved patients receiving flexible doses of Invega, while the second study involved testing with patients assigned to one of two dose levels.

Results showed that patients in the flexible dose study as well as patients in the higher dose group in the 2 dose-level study showed superior results compared to a placebo.

Indicators used for evaluation included positive symptoms, negative symptoms, disorganised thoughts, uncontrolled hostility/excitement, and anxiety/depression.

Approximately half the subjects enrolled received ongoing treatment with a mood stabiliser and/or antidepressant during the studies.