After administration of paliperidone extended-release (ER) tablets, blood levels of the drug were not affected when given with a common antidepressant, according to new data presented today at the 160th Annual Meeting of the American Psychiatric Association. Paroxetine, a selective serotonin reuptake inhibitor (SSRI), is an antidepressant known to interact with several antipsychotic medications. This new study showed there was no clinically significant increase in paliperidone exposure when paroxetine was administered with paliperidone ER.(1) Many medications prescribed for psychiatric illnesses are metabolized in the liver by a specific enzyme called CYP2D6. Administering more than one drug metabolized by CYP2D6 may cause drug-drug interactions. Paroxetine is a potent inhibitor of the CYP2D6 enzyme, and can inhibit the metabolism of some atypical antipsychotic drugs. Approximately 50 percent of patients with schizophrenia have at least one other psychiatric or medical condition requiring medication, most commonly depression.(2) "Drug interactions frequently occur in patients with schizophrenia because this population is often treated for multiple medical and psychiatric conditions," said Dr. Joseph Palumbo, Franchise Medical Leader for Psychiatry, Johnson & Johnson Pharmaceutical Research & Development, L.L.C. "Drug interactions are an under appreciated factor that can reduce optimal treatment outcomes in our patients. This study shows that paliperidone ER can be an important new option for patients with schizophrenia who also require treatment with an antidepressant metabolized through the CYP2D6 system." In this study 60 healthy male patients were randomized to receive either: -- Treatment A: 1 tablet of paliperidone ER 3mg (Day 1) -- or treatment B: 20mg of paroxetine daily (Day 1-13) with 1 tablet of paliperidone ER 3mg on Day 10. After completing their first treatment the patients took no medication for 14 days. Then patients who had received treatment A received treatment B and vice versa. Four days after paliperidone ER administration, the investigators measured the maximum concentration of the drug in the body and total exposure over time to paliperidone ER. No clinically significant increase in paliperidone exposure was seen when paliperidone ER was administered together with paroxetine compared with paliperidone ER given alone. There were no serious adverse events or clinically important changes in laboratory values, vital signs or cardiac parameters. "These results demonstrate that prescribers can administer a CYP2D6- inhibiting antidepressant, paroxetine, with paliperidone ER without having to adjust the dose of paliperidone ER," Palumbo said. "This, when combined with once-daily oral dosing and well demonstrated efficacy, safety, and tolerability, adds to paliperidone ER's usefulness as a new option for the treatment of schizophrenia." The study was sponsored by Janssen, L.P. Janssen is exclusively dedicated to mental health and committed to providing new treatment options, such as paliperidone ER, to patients with psychiatric illnesses. About Schizophrenia Worldwide, it is estimated that 1 person in every 100 develops schizophrenia, one of the most serious types of mental illness. In the United States, there are currently 2,000,000 people with schizophrenia, with men and women affected equally. The disease is marked by positive symptoms (hallucinations and delusions) and negative symptoms (depression, blunted emotions, and social withdrawal), as well by disorganized thinking. Janssen, L.P., based in Titusville, N.J., is the only pharmaceutical company in the U.S. dedicated solely to mental health. The company currently markets prescription medications for the treatment of schizophrenia, bipolar mania, and irritability associated with autistic disorder. For more information about Janssen, L.P., visit