Cariprazine for bipolar depression: What is the number needed to treat, number needed to harm and likelihood to be helped or harmed?

OBJECTIVE

Cariprazine is an oral antipsychotic approved in the US for the treatment of schizophrenia, acute bipolar mania, and most recently, bipolar depression. The aim of this systematic review is to describe the efficacy, tolerability and safety of cariprazine for the treatment of depressive episodes associated with bipolar I disorder (bipolar depression) in adults.

DATA SOURCES

The pivotal registration trials were accessed by querying http://www.ncbi.nlm.nih.gov/pubmed/ and http://www.clinicaltrials.gov, for the search terms "cariprazine" AND "bipolar" AND "depression," and by also querying the Web of Science commercial database for clinical poster abstracts, and by asking the manufacturer for copies of posters presented at congresses. Product labelling provided additional information.

STUDY SELECTION

Double-blind placebo-controlled studies in adults with bipolar depression.

DATA EXTRACTION

Descriptions of the principal results and calculation of number needed to treat (NNT) and number needed to harm (NNH) for relevant dichotomous outcomes were calculated from the available study reports and other sources of information.

DATA SYNTHESIS

Cariprazine differs from other antipsychotics in that it has a 10-fold higher affinity for dopamine D3 receptors than for D2 receptors. Cariprazine's principal active metabolite, didesmethyl-cariprazine (DDCAR), has a half-life of 1-3 weeks and at steady state DDCAR is the predominant circulating moiety. Four double-blind placebo-controlled studies of cariprazine for bipolar depression were found of which three were considered positive and provided data on efficacy; all four studies were used to assess tolerability. Rates of treatment response, defined by a ≥50% reduction from baseline on the Montgomery-Asburg Depression Ratting Scale (MADRS) total score at study endpoint, for the approved doses of 1.5 and 3.0 mg/d (pooled) vs placebo were 46.3% vs 35.9% (NNT 10, 95% CI 7-21). Corresponding rates for remission (defined as MADRS total score ≤10 at endpoint) were 30.2% vs 20.9% (NNT 11, 95% CI 8-22). Discontinuation rates because of an adverse event (AE) were 6.7% for cariprazine (all doses pooled) vs 4.8% for placebo (NNH 51, ns). Product labelling lists the most common AEs as nausea, akathisia, restlessness and extrapyramidal symptoms. Patients receiving cariprazine 3.0 vs 1.5 mg/d were more likely to experience AEs and discontinue the trials because of an AE.

CONCLUSIONS

Cariprazine is the fourth agent approved for bipolar depression in the US. The likelihood to experience a benefit (response or remission) is substantially greater than the likelihood to encounter a discontinuation because of an AE. Direct, head-to-head comparisons with the other approved choices for bipolar depression in the "real world" are needed.