U.S. Court of Appeals for the Federal Circuit has reversed a lower court decision invalidating Sanofi-Aventis’ U.S. Patent No. 5,389,618 for blood thinner Lovenox and threw the decision back to it for further proceedings. Earlier in June 2005, a U.S. District Court in California granted the generic makers summary judgment invalidating the patent. But U.S. Court of Appeals said it was convinced that Aventis intended to deceive the U.S. Patent and Trademark Office, as the generic drug makers had claimed. This patent lawsuit was result of Para IV certifications filed by two generic makers – Teva and Amphastar Pharmaceuticals – seeking permission to market generic version of Lovenox.