Vanda Pharmaceuticals (VNDA) said late Wednesday it sent a letter to US Food and Drug Administration Commissioner Robert Califf, highlighting what it described as the agency's "faulty" review of the company's new drug application for tradipitant to treat gastroparesis.

The FDA previously declined to approve the application and provided the company with a complete response letter in September.

In the letter, Chief Executive Mihael Polymeropoulos expressed surprise at "the sheer disregard for the facts, evidence, and basic scientific principles" contained in the complete response letter.

Polymeropoulos stated that the letter could not "possibly reflect a legitimate regulatory review" as it failed to provide "reasoned explanations or engage with the evidence we presented on its merit-including voluminous evidence from experts."

The FDA has also denied Vanda's request for an advisory committee meeting to consider its application for tradipitant, according to Polymeropoulos.

Polymeropoulos asked Califf to consider his letter.

Gastroparesis is a serious and debilitating gastrointestinal disorder.