Merck & Co has suffered a setback in its ongoing legal battles over the painkiller Vioxx after a jury in New Jersey ordered the firm to pay $47.5 million in damages after finding that the drug was responsible for a plaintiff's heart attack.

Having found earlier this month that Merck failed to sufficiently warn Frederick Humeston, who suffered a heart attack in 2001 at the age of 56, that Vioxx (rofecoxib) increased the risk to health for some users, the jury in Atlantic City pronounced that the company was reckless in promoting the drug and also found that Mr Humeston's doctor would not have prescribed Vioxx to his patient had he been aware of the heart risks associated with the drug.

Mr Humeston has been awarded $18 million in compensatory damages and $2 million will be paid to his wife. Merck, which was described as “reckless" during the verdict will also have to pay an additional $27.5 million in punitive damages.

The US drug giant responded swiftly to the decision from a two-plaintiff, multi-phased trial that the court itself described as "something new." Earlier in March, Mr Humeston's case was tried jointly with that of Brian Hermans, who died of a heart attack in September 2002, but the jury ruled Merck adequately warned the latter man about Vioxx’ health risks.

The company said it will appeal the decision, adding that it has objected to the structure of the trial because of the potential for jury confusion and bias, and Hope Freiwald, a member of the drugmaker’s defence team, said that “in addition to his many individual risk factors for developing coronary disease, Mr Humeston actually had significant coronary disease. This takes decades to develop and had nothing to do with his use of Vioxx."

Kenneth Frazier, Merck’s general counsel, added that “the punitive damages assessed today by the jury are uncalled for because Merck acted appropriately in providing information to the medical, scientific and regulatory communities in a responsible and appropriate manner." The company stressed its belief that the amount set is “without merit, excessive, and not in accordance with constitutional guidance by the US Supreme Court limiting punitive damages.

The loss is Merck's fifth and the company, which is facing 27,000 Vioxx lawsuits, has won nine other cases (one of which was a previous win over Mr Humeston) since 2005. More than 16,000 Vioxx suits are pending before the Superior Court of New Jersey.