Hours after Teva Pharmaceuticals Industries announced that it had started shipments of its generic version of Novartis’ Famvir, a US court slapped a temporary injunction on the Israeli firm preventing it from selling the genital herpes drug.

The day had started well for Teva after it noted that it was starting to ship generic Famvir (famciclovir) after the US District Court for New Jersey denied a motion filed by Novartis for a preliminary injunction. However this was swiftly followed by the US Court of Appeals for the Federal Circuit issuing an order temporarily enjoining Teva from further sales.

The court said that the injunction will remain in place until the consideration of Novartis’ emergency motion for a stay pending appeal takes place and Teva’s response is now due on Tuesday, September 11. This latest chapter in a patent infringement that has been ongoing since April 2005 comes slightly more than a week after the US Food and Drug Administration awarded Teva a 180-day period of marketing exclusivity to sell its copycat version of Famvir.

As for Novartis, it had responded to Teva’s shipping of famciclovir by saying that it will “keep defending its intellectual property rights” on Famvir which the Swiss firm says has various valid US patents until 2015. The company added that Teva’s launch is considered "at risk" since the two companies are still engrossed in the aforementioned patent litigation and the Israeli firm “risks potentially significant damages if Novartis prevails”. A trial date has not been set.

Nevertheless, as a result of Teva's actions, Novartis said that a one-time accounting charge will be taken in the third quarter “for the impairment of intangible assets” and it is expected to be in the range of $250-$300 million.

Court backs Teva over Wyeth in Protonix case

However better news for Teva came when the US District Court of New Jersey denied a motion filed by Wyeth and Altana, now part of Nycomed, for a preliminary injunction related to the Israeli firm’s generic version of the antiulcerant Protonix (pantoprazole).

The court concluded that “sufficient questions about the validity of the patent” had been raised but did not say Wyeth’s view that Protonix is covered in the USA until July 2010 was incorrect. Nevertheless, the US firm’s shares fell 3.8% amid fears that it could lose a major product – US sales of Protonix were about $2.5 billion in the 12 months ended June 30.

However, as in the Novartis/Famvir case, patent litigation over Protonix is ongoing and a trial date has not been set yet. Some analysts believe that Teva, which has received FDA approval for its generic version of the antiulcerant, could press ahead and launch the drug "at risk," but the firm says it is going to “complete a thorough analysis” of the court’s decision “before deciding upon its next course of action”.