A federal judge has denied a bid by Sanofi-Aventis to halt sales of a generic version of its blockbuster blood thinner Lovenox, a move which may help pave the way for the Food and Drug Administration to approve generic biologic drugs.

In a 33-page opinion issued last night, Judge Emmet Sullivan of U.S. District Court for the District of Columbia found Sanofi failed to show the FDA had acted unreasonably in approving an application by Sandoz Inc. to make generic Lovenox. He denied Sanofi’s request for a preliminary injunction that would have forced the FDA to rescind approval of the generic, which has been on the market for a month.