Merck & Co suffered a blow late last week after a US appeals court ruled that a class action suit - brought by non-governmental health plans that paid for prescriptions of the firm’s withdrawn painkiller Vioxx - should go ahead.

The US drugmaker is already facing nearly 10,000 lawsuits brought by people who claim to have suffered side effects as a result of taking Vioxx (rofecoxib), which was taken off the market in September 2004 after it was linked to an elevated risk of heart attack and stroke.

On Friday, the New Jersey appeals court has ruled that the decision by an earlier judge to let the health plans press on with their class action suit, which is trying to recover the cost of supplying the drug to their members, as well as triple damages, according to lawfirm Seeger Weiss LLP. At its height, Vioxx was bringing in $2.5 billion a year to Merck’s coffers.

"The decision applies to all non-governmental, third-party payors in the country, including health insurers, unions, and large employers who paid for Vioxx prescriptions for their plan members," Chris Seeger, lead attorney for the class representative, said in a statement.

Merck said it would appeal once again and take the verdict to the New Jersey Supreme Court.

Mistrial sought in Atlantic City injury suit

Meanwhile, Merck has sought a mistrial in an ongoing lawsuit with two men – Thomas Cona and John McDarby – who blame Vioxx for their heart attacks. The drugmaker claims that lawyers representing the plaintiffs tried to influence the jury in the case by sending them letters thanking them for their diligence during the trial, now in its fourth week.

The trial is a pivotal one for Merck, as for the first time it involves plaintiffs who took Vioxx for at least 18 months. The company maintains that Vioxx is only associated with an increased risk of heart attacks and stroke after prolonged use, but all prior have involved short-term users of the drug.

Merck won two earlier trials involving short-term use, and lost another in which it was order to pay damages of $253 million.