After reviewing research studies and case reports on over 78,000 patients, the researchers explain that the risk of heart failure may be as much as 100% higher in patients receiving thiazolinediones - Avandia® and Actos® are thiazolinediones.
The researchers at Wake Forest University School of Medicine, USA, and the University of East Anglia, United Kingdom considered the two drugs Avandia (rosiglitazone), manufactured by GlaxoSmithKline, and Actos (pioglitazone), and produced by Takeda, which are used to treat type II diabetes. In this type of diabetes the body does not make enough of the hormone insulin, or the cells in the body do not react properly to the hormone. The drugs, which sensitize the body to insulin and lower blood sugar levels, were hailed as a major advance in the fight against the disease.
One in every 50 patients taking either Avandia or Actos over a 26-month period would suffer heart failure and need admission to hospital. The researchers said the drugs could be responsible for additional thousands of cases of heart failure each year.
Sonal Singh, M.D., lead author, said "These drugs have been used by more than 3 million diabetic patients in the U.S. alone, suggesting that several thousand could be harmed." She suggested that fluid retention may be triggering heart failure in some susceptible people - these drugs cause fluid retention.
The risk of heart failure is not linked to dosages, say the researchers. They found that heart failure occurred equally at low and high doses. It took on average 24 weeks from the beginning of drug therapy to the onset of heart failure.
The study follows an earlier warning about Avandia, published in the New England Journal of Medicine in May, which linked the drug to a 43% increased risk of a heart attack. GlaxoSmithKline strongly contested that study's findings, which led to a 22% decline in global sales. Glaxo had argued that "there is no consistent or systematic evidence" linking Avandia to increased risk of heart attack or death.
Following the report it is believed that the drug will be pulled of the market. The Food and Drug Administration in the US will investigate the drug Avandia.
The product labels for both Avandia and Actos warn against their use in people with serious cases of heart failure. They also caution about the raised risk of heart failure when used together with insulin. Co-investigator Curt Furberg, M.D., said "Our findings support current efforts by the FDA to add a black box warning to the labeling for those agents."