Two major court victories for Merck on Thursday pushed the litigation over the painkiller Vioxx closer to conclusion and highlighted the increasing difficulty that plaintiffs’ lawyers were having in winning lawsuits against big drug companies.

A state appeals court in Texas overturned a $26 million jury verdict against the company in a lawsuit brought by Carol Ernst, whose husband, Robert, died in 2001 after taking Vioxx. In reversing the verdict, the appeals court found that plaintiffs had not proved that Vioxx caused Mr. Ernst’s death.

Separately, an appeals court in New Jersey sharply reduced a verdict in another Vioxx case. The court ruled that the jury should not have been allowed to award punitive damages against Merck or to find that Merck had committed consumer fraud. Only compensatory damages of $4.5 million were permitted, the court said.

The rulings on Thursday leave lawyers for plaintiffs with just three victories, all with relatively small awards, in the nearly 20 Vioxx cases that have reached juries. Mark Lanier, a plaintiffs’ lawyer who was involved in both cases decided Thursday, criticized the decisions and promised appeals. But plaintiffs face an uphill battle.