A federal judge has dismissed Amphastar Pharmaceuticals fourth set of counterclaims against Aventis Pharmaceuticals, a subsidiary of Sanofi-Aventis, ruling that federal regulators must take final action on the generics company's bid to produce its own version of the blood thinner Lovenox before the court can act on competition claims.

Judge Mariana R. Pfaelzer, of the U.S. District Court for the Central District of California, dropped the third amended counterclaims without prejudice, telling Amphastar that continuing the case would be futile without final FDA action on its ANDA for generic Lovenox (enoxaparin sodium), according to court documents.

Aventis filed the case, Aventis Pharma et al v. Amphastar, Aug. 4, 2003, to stop the Rancho Cucamonga, Calif.-based Amphastar from marketing its generic version of Lovenox. Aventis later became part of Sanofi.

However, other generic pharmaceutical makers also are attempting to produce and release generic versions of Lovenox, such as Teva Pharmaceuticals of Tikva, Israel, which is seeking FDA approval for its version, as well as Sandoz of Holzkirchen, Germany, and Momenta Pharmaceuticals of Cambridge, Mass.

Currently, there are no approved generic versions of the blood thinner, which had sales of about $3.6 billion last year, according to the Paris-based Sanofi.