Pharmacokinetic characteristics of risperidone ISM for the treatment of schizophrenia

Risperidone-ISM is a novel intramuscular long-acting injectable formulation (LAI) of risperidone approved for the treatment of schizophrenia in adults. Knowledge regarding the pharmacokinetic properties of risperidone-ISM can improve care. We assessed the pharmacokinetic properties of risperidone-ISM. Most importantly, risperidone-ISM achieves therapeutic blood levels within 12-48 hours after the first injection without need for overlapping oral cotreatment, loading dose, or booster injection. Second, the in-situ microparticle (ISM) technology achieves stable blood levels, allowing currently 1-monthly injections. Third, females and patients with higher body mass index may have lower risperidone-ISM clearance, translating into higher risperidone serum levels. Fourth, there are only minimal risperidone-ISM clearance differences between deltoid versus gluteal injections that balance out at steady state. However, aspects including pharmacogenetic and drug-drug interactions involving risperidone-ISM would benefit from further clarification. Risperidone-ISM achieves therapeutic blood levels within 12-48 hours after a single injection, currently lasting for 1 month, easing the initiation of a LAI risperidone formulation in adults with schizophrenia where LAIs remain underutilized. Prescriptions of LAIs, including risperidone-ISM, are likely to increase with an improved understanding of pharmacokinetic profiles and patient acceptability and outcomes, including in real-world settings informing drug selection.