Long-acting risperidone injection: efficacy, safety, and cost-effectiveness of the first long-acting atypical antipsychotic

Abstract

Objective: To review the pharmacokinetics, efficacy, safety, and cost-effectiveness of long-acting risperidone.

Methods: Studies published between January 2000 and October 2006 evaluating the pharmacokinetics, efficacy, safety, and cost-effectiveness of long-acting risperidone were reviewed, as identified from literature searches using Medline and EMBASE. Abstracts and posters on long-acting risperidone presented at key psychiatry congresses and available in the public domain during this time period were also reviewed.

Results: The unique pharmacokinetic profile of long-acting risperidone is derived from the encapsulation of risperidone in a glycolide/lactide matrix in the form of microspheres such that after a single intramuscular injection, significant plasma levels of the drug are achieved after week 3. Steady state, after repeated administration at 2-week intervals, is achieved after 3 injection cycles. Short- and long-term studies have demonstrated that long-acting risperidone (25, 37.5, or 50 mg) is both efficacious and well tolerated in a wide variety of patients with schizophrenia and related psychoses. Most patients can be switched from other oral and long-acting antipsychotic agents without compromising efficacy and safety. Long-acting risperidone may also reduce overall healthcare costs by decreasing rates of relapse and hospitalization.

Conclusion: The assured delivery of an atypical antipsychotic medication with long-acting risperidone has important implications for patient compliance, maintenance of stability, consistency of treatment, and improving patient outcomes including the achievement of remission.

Keywords: efficacy; long-acting injectable risperidone; pharmacoeconomics; pharmacokinetics; safety; schizophrenia.

Figure 1

The dispersion of risperidone from microspheres. Reproduced with permission of Wolters Kluwer Health from Ereshefsky L, Mannaert E. 2005. Pharmacokinetic profile and clinical efficacy of long-acting risperidone: potential benefits of combining an atypical antipsychotic and a new delivery system. Drugs R D, 6:129–37. Figure 1 from page 131.

Figure 2

Schematic representation of plasma concentrations following administration of oral risperidone and long-acting risperidone

Figure 3

Health economic benefits model from the reduced need for institutional care in patients with schizophrenia and schizoaffective disorder that are switched to treatment with long-acting risperidone.