Regulators in the USA have turned down Forest Laboratories and Gedeon Richter's investigational antipsychotic cariprazine, asking for additional clinical trial data.

The Food and Drug Administration has issued a complete response letter regarding the New Drug Application for cariprazine as a treatment for schizophrenia and manic or mixed episodes associated with bipolar I disorder in adults. The agency acknowledges that the drug "clearly demonstrated effectiveness" but indicated that more information, including more trial data, would be needed.

Marco Taglietti, president of the Forest Research Institute, said that "given the complex pharmacokinetics and metabolism of cariprazine, we believe this request was made to better define the optimal dosing regimen to maintain the demonstrated efficacy, while minimising the potential for the development of adverse events generally associated with this class of drug". He added that “the unmet medical need for schizophrenia and bipolar disorder remains high" and the firms plan to meet with the FDA "in the very near future to discuss the CRL and define a path forward".