Drugmaker Sanofi-Aventis is going to take a revenue hit this year after recently stopping production of their newest blood thinner drug. The decision comes after US regulators approved a generic rival to its Lovenox blood thinner.

Sanofi-Aventis recently released a statement saying its shares may decline as much as 4 percent at constant exchange rate. This is a much more bleak estimate than the one given earlier this year stating a increase in revenues of at least 5 to seven percent.

Losing market exclusivity is one of the main reasons that Sanofi-Aventis has been actively seeking to purchase Cambridge, Massachusetts-based Genzyme.

Five or six of their top eight drugs are in the process of or will go generic this year and companies losing drugs are under more pressure to fill that gap, a man with knowledge of the matter stated.

Sanofi-Aventis is the maker of other popular drugs like Actonel, Allegra, Nasacort AQ and Plavix.

Sanofi better come up with some new drugs to fill the gap quickly, or the revenues will continue to fall.