A recently unsealed whistleblower complaint alleges that the U.S. arm of Japanese drugmaker Takeda Pharmaceutical Co. hid the adverse effects of its blockbuster diabetes drug Actos. The lawsuit alleges that Takeda Pharmaceuticals North America Inc. intentionally hid the fact that congestive heart failure was a major side effect of Actos to make Actos seem safer than it is.

Actos is a bestselling diabetes drug that continues to generate billions of dollars in revenue for Takeda. A former medical reviewer for Takeda alleges that the company intentionally failed to report congestive heart failure as a serious risk associated with Actos in the U.S. Food and Drug Administration’s Adverse Event Reporting System.

“Takeda’s motivation to fraudulently report and underreport the serious adverse events was driven by an economic desire to falsely enhance Actos’ safety profile and to increase sales,” the complaint alleges.

The whistleblower also alleges that the company intentionally downplayed the fact that Actos could cause bladder cancer if used for prolonged periods of time. A massive class action lawsuit filed by Actos users with bladder cancer is moving forward against the company.

Takeda has had to pull Actos from several markets due to safety concerns, but denies downplaying any of the serious side effects associated with its drugs.

“Takeda complies with all laws and regulations regarding the reporting of adverse events,” a company spokesman said.

Source: Bloomberg, “Takeda Hid Actos Adverse Effects From Regulators, Suit Says,” David Voreacos, March 7, 2012