Pharmacokinetics and Tolerability Study of Risperidone ISM® in Schizophrenia

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.