Clinical guidelines: Dosing and switching strategies for long-acting risperidone.

41 J Clin Psychiatry 2003;64 (suppl 16) he availability of a long-acting injectable atypical antipsychotic may increase compliance with mediblind, placebo-controlled trial of long-acting risperidone, 25 mg/2 weeks, the lowest tested dose, effectively treated both positive and negative symptoms of schizophrenia. This dose may provide the optimal balance between safety and efficacy because the rates of adverse events were similar for 25 mg/2 weeks of long-acting risperidone and placebo. Regardless of the starting dose, patients who switch from an oral antipsychotic and those who have been taking no antipsychotic should receive oral antipsychotic coverage for the first 3 weeks of long-acting risperidone treatment. This 3-week oral antipsychotic coverage is needed because the first dose of long-acting risperidone takes 3 weeks to be released into the blood and reach therapeutic levels. The appropriate starting dose of long-acting risperidone might be influenced by the patient’s prior antipsychotic dosage history. Patients who are experiencing their first episode of schizophrenia should begin with 25 mg/ 2 weeks, and they should be monitored closely for side effects. Given what is currently known about the pharmacokinetic and pharmacodynamic profiles of long-acting risperidone, a dose lower than 25 mg/2 weeks might also benefit patients who are experiencing their first episode. However, until a lower dose becomes available, the lowest dose administered should be 25 mg/2 weeks, since the entire contents of the dosage vial should be administered to ensure accurate delivery of the drug. Rarely, patients have a clear history of needing high doses of antipsychotics for refractory schizophrenia, e.g., some patients have been stabilized for a long time on a high dose of a conventional depot antipsychotic. For these patients, starting with 37.5 or 50 mg/2 weeks might be appropriate. Generally, clinicians should begin the patient with 37.5 mg/2 weeks. If symptoms persist after the 37.5mg/2 week dose has achieved steady state plasma concentration (i.e., after at least 4 injections of 37.5 mg/2 weeks), the dose could be increased to 50 mg/2 weeks. Some clinicians in countries in which long-acting risperidone is already marketed have started a few severely ill patients at 50 mg/2 weeks. Clinical Guidelines