Carabias LA, et al. - The pharmacokinetics, safety, and tolerability of Risperidone ISM, a new long-acting intramuscular formulation, were characterized for monthly administration without oral supplementation. In this study, risperidone ISM achieved therapeutic levels from the first hours after drug administration and provided a sustained release throughout the 4-week dosing period. It was found to be safe and well tolerated in addition.