The efficacy and safety of the novel antipsychotic cariprazine in acute exacerbation of schizophrenia

Risperidone versus placebo for schizophrenia

BACKGROUND

Risperidone is the first new-generation antipsychotic drug made available in the market in its generic form.

OBJECTIVES

To determine the clinical effects, safety and cost-effectiveness of risperidone compared with placebo for treating schizophrenia.

SEARCH METHODS

On 19th October 2015, we searched the Cochrane Schizophrenia Group Trials Register, which is based on regular searches of CINAHL, BIOSIS, AMED, EMBASE, PubMed, MEDLINE, PsycINFO, and registries of clinical trials. We checked the references of all included studies and contacted industry and authors of included studies for relevant studies and data.

SELECTION CRITERIA

Randomised clinical trials (RCTs) comparing oral risperidone with placebo treatments for people with schizophrenia and/or schizophrenia-like psychoses.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened studies, assessed the risk of bias of included studies and extracted data. For dichotomous data, we calculated the risk ratio (RR), and the 95% confidence interval (CI) on an intention-to-treat basis. For continuous data, we calculated mean differences (MD) and the 95% CI. We created a 'Summary of findings table' using GRADE (Grading of Recommendations Assessment, Development and Evaluation).

MAIN RESULTS

The review includes 15 studies (N = 2428). Risk of selection bias is unclear in most of the studies, especially concerning allocation concealment. Other areas of risk such as missing data and selective reporting also caused some concern, although not affected on the direction of effect of our primary outcome, as demonstrated by sensitivity analysis. Many of the included trials have industry sponsorship of involvement. Nonetheless, generally people in the risperidone group are more likely to achieve a significant clinical improvement in mental state (6 RCTs, N = 864, RR 0.64, CI 0.52 to 0.78, very low-quality evidence). The effect withstood, even when three studies with >50% attrition rate were removed from the analysis (3 RCTs, N = 589, RR 0.77, CI 0.67 to 0.88). Participants receiving placebo were less likely to have a clinically significant improvement on Clinical Global Impression scale (CGI) than those receiving risperidone (4 RCTs, N = 594, RR 0.69, CI 0.57 to 0.83, very low-quality evidence). Overall, the risperidone group was 31% less likely to leave early compared to placebo group (12 RCTs, N = 2261, RR 0.69, 95% CI 0.62 to 0.78, low-quality evidence), but Incidence of significant extrapyramidal side effect was more likely to occur in the risperidone group (7 RCTs, N = 1511, RR 1.56, 95% CI 1.13 to 2.15, very low-quality evidence).When risperidone and placebo were augmented with clozapine, there is no significant differences between groups for clinical response as defined by a less than 20% reduction in PANSS/BPRS scores (2 RCTs, N = 98, RR 1.15, 95% CI 0.93 to 1.42, low-quality evidence) and attrition (leaving the study early for any reason) (3 RCTs, N = 167, RR 1.13, 95% CI 0.53 to 2.42, low quality evidence). One study measured clinically significant responses using the CGI, no effect was evident (1 RCT, N = 68, RR 1.12 95% CI 0.87 to 1.44, low quality evidence). No data were available for extrapyramidal adverse effects.

AUTHORS' CONCLUSIONS

Based on low quality evidence, risperidone appears to be benefitial in improving mental state compared with placebo, but it also causes more adverse events. Eight out of the 15 included trials were funded by pharmaceutical companies. The currently available evidence isvery low to low quality.

Cariprazine, a new, orally active dopamine D2/3 receptor partial agonist for the treatment of schizophrenia, bipolar mania and depression

Cariprazine is a novel drug with partial agonist activity at dopamine D2/3 receptors and six- to eightfold higher affinity for human dopamine D3 over D2 receptors. Results from several placebo-controlled Phase II/III trials in patients with a The Diagnostic and Statistical Manual of Mental Disorders IV diagnosis of schizophrenia or bipolar I disorder suggest that cariprazine is superior to placebo with respect to antipsychotic and antimanic activity. Reports concerning safety and tolerability of cariprazine are mainly favorable, although the rates of treatment-associated adverse events, which most commonly included akathisia and extrapyramidal symptom, are rather high. However, only minor alterations of clinical laboratory values, prolactin concentrations and ECG parameters are reported in cariprazine-treated patients. A new drug application to the U.S. F DA for cariprazine for the treatment of both schizophrenia and manic or mixed episodes associated with bipolar I disorder was submitted in November 2012. A more precise assessment of the clinical properties of this new drug will require additional studies, aimed to compare and contrast cariprazine with other antipsychotic agents.