AstraZeneca has agreed to pay $198m to settle some 17,500 US personal injury claims related to its schizophrenia and bipolar disorder drug Seroquel, the company has announced.

The top-selling medicine, which had worldwide sales of $4.9bn in 2009, accounting for 15 percent of group revenue, has been subject to long-running legal claims after being linked to an increased risk of diabetes.

The average payout of $11,300 per claim is modest by comparison with some past medicine settlements and AstraZeneca investors took the news in their stride.

A further 2,900 cases have been dismissed.

The group did not have a provision for Seroquel settlements as of June 30 but it said the agreements would not affect its 2010 outlook for “core” earnings, since any provision would be disregarded in calculating this underlying measure of profit.

The Anglo-Swedish drugmaker raised its forecast for core earnings per share, which excludes certain restructuring costs and charges, by 30 cents to $6.35 to $6.65 in July after reporting strong second-quarter results.

News of the settlements was no great surprise since sources familiar with the situation said earlier in August that some 5,500 claims had been settled, at that stage, for $55m as part of an ongoing process of mediation.

“We believe it was in the best interest of the company to explore resolving these cases through the mediation process,” said company spokeswoman Abigail Baron.

“We remain committed to a strong defence effort, but will also continue to participate in good faith in court-ordered mediation.”