Sanofi-Aventis said US sales of anti-thrombotic Lovenox were cut nearly in half by the launch of generic competition, an indication hospitals are showing little hesitation in using the copycat version.

Lovenox sales in the US declined 47% to 255 million euros ($354 million), due to the entry of generic enoxaparin at the end of July, Sanofi disclosed in its third-quarter earnings report last week. Outside the US, sales grew 4.6% to 334 million euros ($464 million), accounting for 57% of Lovenox sales in the quarter.

The generic version is being marketed by Novartis unit Sandoz. For the last nine weeks of the July-September period, Novartis reported $292 million in enoxaparin revenue.

“Not only were we first to market, but we were the only generic enoxaparin approved” and still are, said Jeff George, head of Sandoz, who called it the largest launch ever of a generic injectable in the US market.

Momenta, which partnered with Sandoz on development and manufacturing and maintains a profit-sharing arrangement, said today that it earned $44.2 million in the profit share, plus a $5 million milestone payment, and that the generic continues to post strong sales.

The marketing push has included ads only in journals directed at pharmacists but no detailing, a Sandoz spokesperson told MM&M.

Lovenox is one of the leading hospital medications in the US with sales of about $3 billion ($4.3 billion globally). Sanford Bernstein’s Tim Anderson predicted that Sanofi would hang on to a reasonable amount of US market share through the remainder of the year, modeling branded Lovenox sales in the US of 525 million euros for the second half, vs. first-half US sales of 951 million euros.

Teva, which filed its immunogenicity studies one month after Momenta and Sandoz, has an enoxaparin application pending with the FDA.

“Our understanding is that Sanofi has been cutting the effective price of its branded Lovenox to maintain share with purchasers but a new, second generic entrant could frustrate these efforts,” Anderson wrote in an investor note. Another entrant would mean quicker pricing erosion for Lovenox.