Some Vioxx cases earmarked for trial by a New Jersey judge do not involve plaintiffs taking the withdrawn painkiller continuously for 18 months, in spite of being selected as such.

But at least one of 12 cases listed by the judge last week does include claim of injury from Vioxx after taking the drug for 18 months, say defence attorneys. This would mark the first 18-month case acknowledged by Merck, which withdrew Vioxx a year ago after finding increased heart risks.