In a ruling in the US state of New Jersey on Thursday the nine-member jury also found that Merck did not misrepresent, suppress or conceal information about increased risks of heart attack and stroke from the pain and arthritis medicine.
"It's a terrific victory for Merck," said Ned Riley, chief executive of Riley Asset Management.
"It might open the door for Vioxx to come back on the market with some labelling [changes]. It may not be the lost drug everyone anticipated."
Last August, in the first Vioxx case to go to trial, a Texas jury found Merck liable for the death of a 59-year-old Vioxx user and awarded his widow $253 million in damages.
Merck is appealing that decision.
The jury reached its decision after only about eight hours of deliberation, following a seven-week trial in which lawyers for 60-year-old postal worker Frederick Humeston argued that Vioxx caused his 2001 heart attack.
Merck shares were up to $29.78
on the New York Stock Exchange
Vickie Heintz, a 40-year-old juror from Mays Landing, New Jersey, said Humeston had "way too many health issues," to win his case.
"If you looked at his medical records over the past 20 years, it was riddled with a history of medications and health problems. Stress absolutely played a role," Heintz said.
Merck's lawyers had argued that the postal worker was under
tremendous job-related stress at the time of his heart attack.
"Frederick Humeston would have suffered a heart attack when
he did, whether he was taking Vioxx or not," said Jim Fitzpatrick, one of Merck's lawyers.
The case was being closely watched as a potential indicator of future Vioxx litigation as Merck is facing more than 6500 lawsuits from former Vioxx users who claim to have been harmed by the drug.
"Merck would have been in a desperate situation if it had not won this case because a negative verdict would have encouraged waves of other plaintiffs to come forward," said Steve Brozak, an analyst with WBB Securities LLC.
The plaintiff's side had accused Merck of hiding for years evidence that Vioxx caused increased heart risks in order to protect huge profits.
The drugmaker said it pulled the $2.5 billion-a-year drug from the market in September 2004 as soon as it had clear data showing that long-term Vioxx use doubled the risk of heart attacks and strokes.
"This case involved a person who only used Vioxx for a short amount of time and used it intermittently," said Albert Rauch, an analyst for AG Edwards. "If Merck would have lost this, there would not be much they could win."
Humeston had taken the drug for about two months for knee pain from an old Vietnam war wound, while the study that led to the Vioxx withdrawal last year found increased heart risk only after 18 months of continuous use.
"There will be other Vioxx trials and we will vigorously defend them one by one over the coming years"
Merck general counsel
"I wish to impart to other plaintiffs, do not let this deter you because Vioxx is a bad product," Humeston said after the verdict.
More than 2700 of the cases against Merck were filed in New Jersey and Judge Carol Higbee, who presided over the Humeston case, is expected to oversee the bulk of them.
The first federal Vioxx case is scheduled to go to trial on 28 November before US District Judge Eldon Fallon of New Orleans, who is operating out of Houston because of Hurricane Katrina.
"There will be other Vioxx trials and we will vigorously defend them one by one over the coming years," Merck general counsel Kenneth Frazier said in a statement.
Merck has set aside $675 million to fight the Vioxx lawsuits.
Analysts are saying Merck could still eventually have to pay anywhere from $5 billion and $50 billion to cover potential liability from the growing wave of Vioxx lawsuits.
Merck shares were up $1.37, or 4.8%, to $29.78 on the New York Stock Exchange after climbing as high as $30.50.