Background: Positive and Negative Syndrome Scale (PANSS) data from a pivotal phase 3 study in participants with schizophrenia of RBP-7000, a recently marketed long-acting subcutaneous injectable risperidone formulation, were examined to determine if dose-response relationships existed for different items of the PANSS.
Methods: Changes in the 30 PANSS items were analyzed individually and using the 5 factor-analysis-derived dimensions defined by Marder and colleagues. Subgroups of patients who could benefit from the RBP-7000 120 mg dose were investigated.
Results: 337 participants were randomized and received study medication (RBP-7000 90 mg n = 111, RBP-7000 120 mg n = 114, placebo n = 112). Dose-dependent responses were observed in items from the study-specified PANSS positive and general psychopathology exploratory subscales. Dose-dependent responses were observed across all 5 Marder dimensions, with the largest effect sizes observed with the 120 mg dose in the uncontrolled hostility/excitement (UHE) and anxiety/depression dimensions. Participants with baseline UHE dimension scores ≥ 9 demonstrated greater improvement in PANSS total score at the 120 mg dose compared to the 90 mg dose.
Conclusions: RBP-7000 demonstrated efficacy across both the primary and exploratory PANSS study endpoints and the post hoc Marder dimensions. Schizophrenia patients with higher baseline Marder UHE scores may benefit from initiation of treatment at the 120 mg dose.
Trial Registration: ClinicalTrials.gov identifier: NCT02109562.
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