Just one more example of investor dissatisfaction with JP Garnier. The North Yorkshire Pension Fund and the Avon Pension Fun, which together manage more than $6 billion in assets, are vying to be lead plaintiffs in a US class-action lawsuit filed against the drugmaker for misleading investors over the risks of its Avandia diabetes pill.

The lawsuit seeks unspecified damages related to a slide in the group’s share price that followed a study published in May in the New England Journal of Medicine claiming that Avandia raised the risk of heart attack by 42 per cent. The findings, denied by GSK, wiped about $18 billion off its market capitalisation.

The two UK funds claim they lost roughly $5 million. “We are joining [the lawsuit] because it is in our members’ interests to do so,” Neil Sellstrom, of the North Yorkshire fund, tells The Times of London.

The lawsuit alleges Glaxo “engaged in a scheme to deceive the market and a course of conduct that artificially inflated GSK’s stock price” and “failed to adequately disclose” important risk info. Glaxo is accused of “fraud” and “deceit.” A spokesman for GSK said that the company believed the lawsuit had no merit and would vigorously defend itself.

Glaxo investors are increasingly unhappy with the drugmaker’s share price and some are agitating for Garnier to sell off various pieces, such as the consumer healthcare business or vaccines research. For his part, the indefatigable Garner refuses to consider such moves and last week brushed aside the criticism.

Garnier, however, continues to suffer setbacks. At week’s end, the FDA further delayed approval of Entereg, an experimental constipation med that’s being developed by Glaxo’s partner, Adolor. The agency previously issued an approvable letter back in June, which itself was a disappointment.