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Objective: To evaluate the feasibility of conducting a large clinical trial within the Rwandan mental healthcare system that would establish the safety, efficacy and benefit of paliperidone palmitate once-monthly (PP1M) and once-every-3-months (PP3M) long-acting injectable formulations in adults with schizophrenia., Study Design: An open-label, prospective feasibility study., Setting/participants: 33 adult patients with schizophrenia were enrolled at 3 sites across Rwanda., Interventions: The study design included 3 phases of treatment: an oral run-in to establish tolerability to risperidone (1 week), lead-in treatment with flexibly dosed PP1M to identify a stable dose (17 weeks) and maintenance treatment with PP3M (24 weeks)., Primary and Secondary Outcome Measures: Feasibility endpoints included compliance with governmental and institutional requirements, acceptable supply chain delivery and proper onsite administration of risperidone/PP1M/PP3M, adequate site infrastructure, adequate training of clinical staff and successful completion of study procedures and scales. A variety of study scales were administered to assess outcomes relevant to patients, caregivers, clinicians and payers in Rwanda and other resource-limited settings., Results: This study was terminated early by the sponsor because certain aspects of study conduct needed to be addressed to maintain Good Clinical Practice requirements and meet regulatory standards. Results identified areas for improvement in study execution, including study governance, site infrastructure, study preparation and conduct of procedures, study budget and study assessments. Despite the identification of areas in need of adjustment, none of these limitations were considered insurmountable., Conclusions: This work was designed to strengthen global research in schizophrenia by building the capacity of researchers to prepare and conduct pharmaceutical trials in resource-limited settings. Although the study was ended early, modifications motivated by the results will facilitate the successful design and completion of more comprehensive studies, including an ongoing, follow-up interventional trial of PP1M/PP3M in a larger population of patients in Rwanda., Trial Registration Number: NCT03713658., Competing Interests: Competing interests: AK is an employee of Janssen Scientific Affairs, LLC, IT is an employee of Janssen Research and Development, LLC, and EA is an employee of Johnson & Johnson Global Public Health; all hold stock in Johnson & Johnson, Inc. EH was an employee of Janssen Research and Development, LLC, at the time the trial was conducted. AS was an employee of Janssen Research & Development, Beerse, Belgium, at the time the trial was conducted and holds stock in Johnson & Johnson, Inc. LA was an employee of Janssen Scientific Affairs, LLC, at the time the trial was conducted and is currently employed by Denovo Biopharma, LLC; he holds stock in Johnson & Johnson, Inc., and Denovo Biopharma, LLC. BM and VS-S were employees of Johnson & Johnson Global Public Health at the time the trial was conducted and hold stock in Johnson & Johnson, Inc. JDI, YK and RB report no conflicts of interest., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: This double-blind (DB), randomized, parallel-group study was designed to evaluate efficacy and safety of paliperidone palmitate 6-month (PP6M) formulation relative to paliperidone palmitate 3-month (PP3M) formulation in patients with schizophrenia., Methods: Following screening, patients entered an open-label (OL) maintenance phase and received 1 injection cycle of paliperidone palmitate 1-month (PP1M; 100 or 150 mg eq.) or PP3M (350 or 525 mg eq.). Clinically stable patients were randomized (2:1) to receive PP6M (700 or 1000 mg eq., gluteal injections) or PP3M (350 or 525 mg eq.) in a 12-month DB phase; 2 doses of PP6M (corresponding to doses of PP1M and PP3M) were chosen., Results: Overall, 1036 patients were screened, 838 entered the OL phase, and 702 (mean age: 40.8 years) were randomized (PP6M: 478; PP3M: 224); 618 (88.0%) patients completed the DB phase (PP6M: 416 [87.0%]; PP3M: 202 [90.2%]). Relapse rates were PP6M, 7.5% (n = 36) and PP3M, 4.9% (n = 11). The Kaplan-Meier estimate of the difference (95% CI) between treatment groups (PP6M - PP3M) in the percentages of patients who remained relapse free was -2.9% (-6.8%, 1.1%), thus meeting noninferiority criteria (95% CI lower bound is larger than the pre-specified noninferiority margin of -10%). Secondary efficacy endpoints corroborated the primary analysis. Incidences of treatment-emergent adverse events were similar between PP6M (62.1%) and PP3M (58.5%). No new safety concerns emerged., Conclusions: The efficacy of a twice-yearly dosing regimen of PP6M was noninferior to that of PP3M in preventing relapse in patients with schizophrenia adequately treated with PP1M or PP3M., Trial Registration: Clinical Trials.gov identifier: NCT03345342., (© The Author(s) 2021. Published by Oxford University Press on behalf of CINP.)

The objective of the study is to investigate whether dopamine D2 receptor occupancy by risperidone and plasma levels over time can account for therapeutic efficacy and the latency period to response. Thirty-eight examinations with (123)I-IBZM single photon emission computed tomography were performed on 22 patients with schizophrenia, at diagnosis, 48 h after starting risperidone treatment and at a stable dose. Risperidone plasma levels were determined and psychopathologic evaluations (Brief Psychiatric Rating Scale, Positive and Negative Syndrome Scale) were carried out. No differences in the striatal/occipital (S/O) ratio or plasma levels were found between examinations at the 48-h time point and when a stable dose level had been established, so these parameters could not account for the latency period required for clinical response. D2 receptor occupancy at 48 h correlated positively with clinical improvement after 2 weeks of treatment. Therefore, if these results are confirmed, D2 receptor occupancy at the beginning of treatment with risperidone may be a predictor of subsequent clinical response.