Merck was hanging yesterday after a Los Angeles judge declared two mistrials when the jury failed to come down on either side of the fence in the cases of two men who claimed their heart attacks had been linked to Vioxx (rofecoxib) use.

Lawrence Appell of Arizona told the jurors he used Vioxx for 18 months before suffering a heart attack in 2000, at age 51, although he continued to use the drug until 2004. The other plaintiff, Rudolph Arrigale of California, alleged he took Vioxx for less than five months before his heart attack five years ago at age 72.

“Both plaintiffs failed to prove their case," said Thomas Yoo of Reed Smith, a member of the defense team. "We are fully prepared to defend these cases if they are tried again."

And Merck has reason to feel optimistic, though it acknowledges each and every case is different. In December 2005, a judge in New Orleans declared a mistrial; the case was subsequently retried but a new jury found in favour of Merck.

Merck is also quick to point out that, as of September 30 last year, more than 3,000 claims have been dismissed even before being scheduled for trial and 1,100 of these cannot be filed again – although the same cannot be said for the remaining 2,000.

Overall, of the 28 plaintiffs whose cases have been tried in a court of law, six claims have been dismissed, seven were withdrawn by the plaintiffs themselves, Merck has won in nine and lost in four (and is appealing or seeking judicial review in these cases). There have been three mistrials.