The U.S. Food and Drug Administration has announced it is updating the drug's labeling to reflect this concern.
The drug, which is made by Takeda Pharmaceuticals, is marketed under a number of brand names, including Actos, Actoplus Met, Actoplus Met XR, Duetact, and Oseni.
Pioglitazone is approved to improve blood sugar control, along with diet and exercise, in adults with type 2 diabetes.
Pioglitazone works by increasing the body’s sensitivity to insulin, a natural hormone that helps control blood sugar levels. Untreated, type 2 diabetes can lead to serious problems, including blindness, nerve and kidney damage, and heart disease.
The agency added a warning about the increased risk for bladder cancer to the drug's label in 2011 based on interim results of a 10-year epidemiological study of patients with diabetes.
The data suggested that this cancer risk rose as the dose and treatment duration increased, the agency says.
According to the FDA, the research on the drug is complicated and had yielded conflicting results.
But, after a review, the agency said in a news release that it has concluded – again –that pioglitazone may be linked to an increased risk for bladder cancer, and it is updating the medication’s label to describe the additional studies it reviewed.
The revised labeling advises clinicians not to prescribe pioglitazone for patients with active bladder cancer and to exercise caution when using it in patients with a history of the cancer.
In addition, the FDA urges patients to contact their health care professionals if they experience any of the following signs or symptoms after starting pioglitazone, as these may be due to bladder cancer:
- Blood or a red color in the urine
- New or worsening urge to urinate
- Pain when urinating.