Cost Comparison of Atypical Antipsychotics: Paliperidone ER and Risperidone.

Purpose: Paliperidone and risperidone are atypical antipsychotics that are structurally and therapeutically similar. Risperidone is metabolized by the liver via cytochrome (CYP) 2D6 to an active metabolite, 9-hydroxyrisperidone. The atypical antipsychotic paliperidone is 9-hydroxyrisperidone formulated separately as an extended-release (ER) tablet and is considerably more expensive than risperidone. The purpose of this retrospective drug utilization review is to evaluate the prescribing patterns of paliperidone ER and evaluate potential cost savings by converting paliperidone ER orders to risperidone at an inpatient psychiatric hospital's formulary. Methods: This retrospective drug utilization review includes 100 patients, older than 18 years old, who were prescribed oral paliperidone ER at an inpatient, psychiatric hospital between January 1, 2017, and June 2, 2017. The data were collected through the electronic medical records. Patients who were prescribed oral paliperidone ER and refused to take paliperidone ER were excluded from the study population. The cost of each patient's oral paliperidone ER pharmacotherapy was calculated using average wholesale prices. An equivalent total dose of risperidone therapy was calculated using a 2:3 paliperidone ER to risperidone conversion. The cost savings were then analyzed by comparing the total costs of paliperidone ER with risperidone therapy. Results: The results indicate that from January through June 2017, approximately 68% of all paliperidone ER utilization was for its approved indication of schizophrenia and schizoaffective disorder. The other 32% of utilization was either off-label or for approved indications of risperidone. The total paliperidone ER therapy cost for 100 patients was approximately $17 000, while the cost of risperidone therapy would be approximately $400 for the same patients over 6 months. Overall, this would provide an estimated cost savings of over $33 000 per year or about $169 in savings per patient. Conclusion: The study analysis demonstrates that there are opportunities for cost savings through therapeutic interchange of paliperidone ER to risperidone.