This was a multicenter, open-label, two-arm, parallel-design, repeat-dose clinical study designed to evaluate the PK, safety, and tolerability of Risperidone ISM®, a new long-acting injectable formulation of the licensed drug risperidone, administered in the gluteal muscle or the deltoid muscle. Participants were patients with a diagnosis of schizophrenia capable of understanding, signing, and consenting to study participation on their own.~Objectives:~Primary Objective~• To characterize the pharmacokinetics (PK) of the injectable intramuscular (IM) long-acting formulation of risperidone over four IM injections in the gluteal and deltoid muscle at 28 day intervals and at one dose strength (75 mg) in patients with schizophrenia.~Secondary Objectives~To document the attainment of steady-state exposure by the injectable formulation ISM® of risperidone over four IM injections in the gluteal and deltoid muscle at 28-day intervals and at one dose strength (75 mg) in patients with schizophrenia.~To perform a descriptive comparison of the PK data between the gluteal and the deltoid muscle administration of the injectable formulation ISM® of risperidone over four IM injections at 28-day intervals and at one dose strength (75 mg) in patients with schizophrenia.~To evaluate the safety and tolerability of the injectable formulation ISM® of risperidone after four IM injections in the gluteal muscle or deltoid muscle at 28-day intervals at one dose strength (75 mg) in patients with schizophrenia.~Exploratory Objectives~To explore the efficacy of once every four weeks of the injectable formulation ISM® of risperidone after four IM injections in the gluteal muscle or deltoid muscle at 28-day (± 1 day) intervals at one dose strength (75 mg) in patients with schizophrenia.~To characterize patients' metabolic phenotype (cytochrome P450 [CYP]2D6, CYP3A4) to explain any potential unexpected outlying PK value, and/or explore its relationship with any potential safety or tolerability issue.
To characterize the pharmacokinetics (PK) of the injectable intramuscular (IM) long-acting formulation (in situ microparticle, ISM) of risperidone over four IM injections in the gluteal and deltoid muscle at 28-day intervals and at one dose strength (75 mg) in patients with schizophrenia.