The Food and Drug Administration (FDA) has concluded that the use of pioglitazone, a type 2 diabetes treatment, may be linked to an increased risk of bladder cancer. 

Pioglitazone, a thiazolidinedione, is approved as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes. It is found in the following medications.

While the prescribing information for these drugs had already contained warnings about the risk for bladder cancer, the FDA has now approved updates to describe the additional studies that have been reviewed.  

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The FDA initially informed the public about the risk in September 2010 and June 2011 based on interim data from a 10-year epidemiologic study. In 2010, the FDA also communicated that bladder tumors were seen in animal studies after exposure to pioglitazone. Labels for the pioglitazone-containing drugs were then modified in August 2011 to reflect this risk of bladder cancer. Manufacturers were required to continue the 10-year study after updating their labels. 

The FDA reviewed more studies that evaluated the risk of bladder cancer in patients treated with pioglitazone but found conflicting results. The 10-year epidemiological study conducted by Takeda did not find a higher risk of bladder cancer with pioglitazone use but another study (Tuccori et al.) found statistically significant trends in bladder cancer risk with increasing cumulative duration and dose of pioglitazone. A different randomized controlled trial, PROactive, found a higher risk during the study period but the risk was not sustained during the follow-up period after trial completion. Moreover, conflicting data was seen regarding whether the risk of bladder cancer was impacted by the duration of use and/or total dose over time of pioglitazone. 

In general, the updated review suggests that pioglitazone may be associated with an increased risk of bladder cancer. 

The most recent FDA communication recommends healthcare professionals not use pioglitazone in patients with active bladder cancer and should carefully consider the risks and benefits prior to using pioglitazone in patients with a history of bladder cancer. If patients experience blood or red color in the urine, a new or worsening urge to urinate, or pain when urinating after initiating pioglitazone treatment, they should contact their healthcare professional.

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