Monthly dosage of extended-release risperidone (RBP-7000) through subcutaneous injections for treatment of schizophrenia is mostly safe, according to a study published in the Journal of Clinical Psychopharmacology.

The current study is a part of the phase 3 program for RBP-7000, which consisted of a double-blind, placebo-controlled trial and the present, 52-week open-label study of monthly subcutaneous RBP-7000 120 mg. A total of 500 participants were enrolled in the study, of which 92 were patients who were rolled over from the previous double-blinded trial and 408 were de novo participants (Positive and Negative Syndrome Scale total score, ≤70) with stable schizophrenia. Participants of the study were adults 18 to 65 years of age who met the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria for schizophrenia. During this 52-week open-label study, patients who were rolled over were administered 11 monthly subcutaneous injections of RBP-7000 120 mg and de novo participants received up to 13 injections. If the psychiatric symptoms worsened, participants were allowed a single dose modification to 90 mg for tolerability and a subsequent single dose modification to 120 mg at the investigator’s discretion. Of the 92 rollover participants, 30.4% were placebo (n=28), 33.7% were given RBP-7000 90 mg (n=31), and 35.9% took RBP-7000 120 mg (n=33). Only 46.8% of patients completed this study. The number of placebo group participants who completed the study was approximately half that of the other groups.

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The majority of participants (73.4%) reported 1 or more treatment-emergent adverse events. The most common treatment-emergent adverse events (≥5%) were injection-site pain (13.0%) and weight increase (12.8%), schizophrenia (7.8%), insomnia (7.0%), injection-site nodule (6.8%), akathisia (6.0%), injection-site induration (5.8%), upper respiratory tract infection (5.2%), and headache (5.0%). It was reported that 34 participants (6.8%) experienced a serious adverse event and 4 deaths were reported, none of which was considered related to the study drug. The results also showed that there were no clinically significant changes in extrapyramidal symptom scales or measure of suicidality throughout the study. The results also supported the previous evidence that 8 weeks of treatment with either RBP-7000 90 mg or RBP-7000 120 mg significantly improved Positive and Negative Syndrome Scale score total scores and the data also suggest that there is continued improvement in acute schizophrenia symptoms even after several months of exposure to RBP-7000.

According to the investigators, an important limitation of the study is the open-label nature of the study. Secondly, the participants of the rollover group already could tolerate chronic treatment with atypical antipsychotics, which could have caused some degree of recruitment bias. Finally, the overall discontinuation of 53% might affect the generalization of the results.

The investigators concluded that overall, the safety profile of RBP-7000 subcutaneous treatment was consistent with that of oral RBP-7000 and clinical outcomes measures either improved or remained stable throughout the study.

Disclosure: This clinical trial was supported by Indivior Inc. Please see the original reference for a full list of authors’ disclosures.

Reference
Andorn A, Graham J, Csernansky J, et al. Monthly extended-release risperidone (RBP-7000) in the treatment of schizophrenia: results from the phase 3 program [published online July 23, 2019]. J Clin Psychopharmacol. doi:10.1097/jcp.0000000000001076