The federal district court in the Eastern District of Virginia has ruled that Synthon IP obtained, by inequitable conduct, two US patents alleged to cover a process and an intermediate compound used to make the active ingredient in Pfizer's widely-prescribed hypertension medication, Norvasc, Pfizer said.

Pfizer said the court found that Synthon had knowingly failed to disclose to the US patent office Pfizer publications and other information it had in its possession that described the process Synthon sought to patent. "It's very difficult to meet the standards for establishing inequitable conduct," said Allen Waxman, Pfizer's general counsel. "But in this case it is clear that Synthon improperly used Pfizer's own published material to obtain a patent that it then tried to enforce against us."

Pfizer said, it intends to seek attorneys' fees from Synthon. The case may be appealed. Synthon had asserted that Pfizer's process for manufacturing Norvasc a process Pfizer had not only published but has been using for 15 years infringed Synthon patents issued in 2003 and 2005. In August of last year, a jury unanimously ruled that one of those patents was not infringed by Pfizer and was invalid on multiple grounds; principally because it was based on Pfizer's prior published work. Synthon had dropped its claim of infringement on the second patent prior to trial.