A US court has reached a split verdict in the latest case brought against the manufacturer of the painkiller Vioxx.
The jury ruled John McDarby should receive compensation
A New Jersey jury found that Merck & Co was liable for one user's subsequent heart attack and ordered the firm to pay $4.5m (£2.5m) in compensation.
A second man will not be compensated after it was ruled Vioxx use was only one of several factors in his illness.
The first verdict is the second Merck has lost, while it has won two earlier cases, one after a mistrial.
The latest trial was the first involving plaintiffs who had used the treatment for more than 18 months.
Merck voluntarily withdrew Vioxx - used to treat rheumatic pain - from sale in 2004, after tests showed that its use may lead to increased incidences of heart attacks and strokes.
PREVIOUS VIOXX TRIALS
August 2005: Merck ordered to pay a Texas widow $253m in damages
November 2005: Merck cleared in the case of Idaho postal worker
February 2006: Merck found not guilty in the case of the death of Richard Irvin, following an earlier mistrial
Merck denies accusations of negligence in its handling of Vioxx, saying it provided full and clear information to consumers about the drug and its potential risks.
However, in the latest trial, a jury found the firm failed to adequately warn both men about the risk factors associated with the drug.
Use of Vioxx directly contributed to John McDarby's heart attack, the jury found on Wednesday after the month-long trial.
It ordered Merck to pay $3m in compensation to Mr McDarby, 77, and $1.5m to his wife.
Mr McDarby, who took Vioxx for four years, broke his hip as a result of his heart attack and, according to his lawyers, is now confined to a wheelchair.
Merck was cleared of liability in the case of Thomas Cona
However, the court concluded that Thomas Cona, a 60 year-old businessman who used Vioxx for two years, should only receive $45 in compensation for the cost of medication.
The jury is expected to decide on Thursday whether Merck should face punitive damages.
"Merck will present evidence it believes shows that the company submitted to the US Food and Drug Administration all relevant and material information concerning Vioxx," the firm said in a statement, ahead of Thursday's hearing.
Last August, a Texas jury ordered Vioxx to pay $253m to the widow of a Vioxx user after finding the drug contributed to her husband's death.
In two other cases, Merck has been cleared of any liability, while another case is currently being heard in Texas.