(Patients taking pioglitazone (Actos) for more than a year may have an increased risk of bladder cancer, according to an FDA interim review of an ongoing epidemiological study. The warning came just days after two European countries banned use of the drug. The label for the diabetes drug pioglitazone (Actos) will now warn patients about a potential increased risk for bladder cancer when taken for 1 year or more, the FDA announced on Wednesday. Last week, France decided to pull pioglitazone off the shelves over similar concerns, and Germany recommends that new patients not start using the drug.
Five-year data show that although there's no overall increased risk of bladder cancer, patients with the longest exposure to and the highest cumulative dose of the drug were found to be at greater risk, The five-year analysis included data on 193,099 diabetic patients who were treated with pioglitazone for a median of two years.
Patients on the drug for more than a year had a 40% increased risk of bladder cancer compared with those who never took it, although the finding was of borderline significance. The significance increased after two years of treatment (OR 1.4, 95% CI 1.03 to 2.0) but the FDA acknowledged that the finding was still of "nominal" statistical significance. The agency said therapy longer than a year was associated with 27.5 excess cases of bladder cancer per 100,000 person-years of follow-up, compared with never using the drug.
Pioglitazone is now the second medication in the thiazolidinedione (TZD) class to be associated with serious side effects within the past year. Last fall, the use of rosiglitazone (Avandia) wasseverely restricted in the U.S. and subsequently in other parts of the world because of concerns about an increased risk of heart attack.
Some researchers suspect that this may prompt physicians to back away from prescribing the class at all, moving toward newer therapies, particularly the incretins, when metformin alone is no longer working for type 2 diabetes patients. Researchers say the latest warning probably won't change that process, but there doesn't appear to be much interest in choosing between what some see as the lesser of two evils with the drug class.
That worry is shared by The Endocrine Society and the American Association of Clinical Endocrinologists. In a joint statement with the American Diabetes Association, the organizations emphasized that patients currently taking pioglitazone should remain on the drug unless otherwise advised by a doctor. "Stopping diabetes medications can result in higher levels of blood glucose that may cause serious short-term health problems and could increase the risk of diabetes-related complications in the long term," the organizations said.
The FDA began its review of pioglitazone and the potential risk of bladder cancer last September and said it will continue to monitor data until the full 10-year study is complete.)
© Journal of Medical Sciences 2012
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