Otsuka received a warning letter after an FDA review of its pharmacology aid for its Abilify tablets showed the company made false or misleading claims about the drug as well as unsupported superiority claims.

According to the letter, promotional material for the company’s Abilify — which is intended to treat bipolar disorder and major depressive disorder (MDD) — contains misleading claims and presentations about the drug, thus misbranding it.

The FDA wrote that the pharmacology aid deceptively implies a more significant degree of certainty about how the drug works in humans than is actually known. According to the letter, Otsuka suggests a “definitive understanding of Abilify’s ability to modulate dopaminergic and serotonergic activity” even though this hasn’t been established. Cited in the letter is the Clinical Pharmacology section of the PI for Abilify, which states “the mechanism of action of aripiprazole … is unknown.” The OPDP also targets footnoted information that it says is not sufficient to clarify the misleading claims in the body of the aid and the references used by Otsuka to support its claims, stating they’re insufficient.

The letter also faulted the company for the claims and presentations in its promotional material that misleadingly imply the drug offers advantages over other MDD or bipolar treatments despite the fact that this hasn’t be shown. The OPDP states that the pharmacology aid contains comparative presentations suggesting Abilify has a clinical advantage because of its pharmacology, while there’s no evidence to support that implication.