Fresh diabetics drug fears weigh on GSK

Avandia, the diabetes drug developed by GlaxoSmithKline, the UK's largest pharmaceutical group, came under fresh attack yesterday as another US medical journal published two negative studies into the drug's cardiovascular side-effects.

The Journal of the American Medical Association published two comparative studies between Avandia and Actos, the only major competing diabetes drug made by Takeda Pharmaceuticals. One study claimed that rather than increasing the likelihood of cardiovascular problems, Actos appears to protect patients from heart disease and strokes, while the other suggested Avandia does indeed contribute to heart attacks. However, one of the studies was funded by Takeda and three of the four authors received support and consulting fees from Takeda.

In a written statement, GSK said: "We believe conclusions drawn from the most recent meta-analyses... do not confirm a difference in the safety profile of Avandia and Actos. These analyses reflect limitations that are common to all meta-analyses, by the authors' own admission. These analyses do not yield data robust enough to guide doctors in selecting appropriate diabetes treatments." A meta-analysis is one drawn from studying existing data rather than by analysing new research.

The studies are come as yet another blow to Avandia. Sales of the drug have dived since May, when the New England Journal of Medicine raised concerns over its safety. Although the Federal Drug Administration did not removeAvandia from the market after a review in July, it is yet to decide whether the drug should carry a "black box" warning, or restrict sales. The drug could still be pulled from the market – a first for a major pharmaceutical blockbuster treatment.

Sales of Avandia fell 22 per cent to £349m in the first quarter. Analysts believe further FDA warnings over the safety of Avandia could extinguish hopes for a rebound in sales.