GlaxoSmithKline has once again jumped to the defence of Avandia, this time in response to a study which claims that treatment with the controversial diabetes drug can lead to an increase in the risk of bone fractures and osteoporosis.

A paper published online in Nature Medicine, involved a study conducted in mice by a team of researchers at the Salk Institute for Biological Studies in La Jolla, California and its senior author Ronald Evans, claimed that long-term Avandia (rosiglitazone) usage in the treatment of type 2 diabetes “may cause osteoporosis due to both increased bone resorption and decreased bone formation”.

However, Prof Evans added that “because Avandia is effective in controlling glucose and restoring the body's sensitivity to insulin, we do not recommend that people stop their treatment. You must balance the benefits against the complications."

Nothing new in findings
GSK moved swiftly in response, saying that the study “adds further context on the possible involvement of thiazolidinediones, such as Avandia and Takeda’s Actos (pioglitazone), in osteoclast activity”. However, its findings would appear to present nothing new.

The UK-based drugs major said that the TZD class of medicines “has already been widely studied in relation to bone fracture and fractures have been previously reported in female patients taking this class of drugs”. Furthermore, there is a precaution for fracture on the labels of both Avandia and Actos and “this information has been widely communicated for both products through dear healthcare professional letters in Europe and the USA”, GSK noted.

The company also noted that it evaluated the rates of bone fractures in a post hoc analysis of data from its massive ADOPT trial which showed that more women with bone fractures at peripheral sites (foot, hand and upper arm) were observed in the Avandia group versus those in the metformin or glyburide groups. However, “these peripheral fractures are not typical of those associated with osteoporosis”, it added.

Furthermore, prior to this aforementioned analysis, there were no findings in the rosiglitazone clinical trial database to suggest that people with type 2 diabetes taking the drug were at increased risk for fractures. In addition, GSK claimed that the evidence to date from ADOPT shows no increase in spine or hip fractures, which are typically associated with osteoporosis, in patients treated with Avandia.

The company concluded by saying that it has “a comprehensive pre-clinical and clinical programme to better understand the underlying mechanism of the fractures” and the European Medicines Agency has agreed that the project is adequate.

This latest development comes just after the US Food and Drug Administration said that Avandia needs to carry a black box warning that will carry additional information stating that it may potentially increase the risk for heart attacks. The treatment has suffered a torrid time at the hands of its critics ever since a meta-analysis in May that was published in the New England Journal of Medicine raised concerns about cardiovascular risk and sales of the drug have suffered ever since.