Sanofi-Aventis SA isn’t taking ‘No’ for an answer.

After having its $69-a-share bid for Genzyme Corp. termed as too low, France’s largest drug maker has launched a $18.5 billion hostile takeover offer.

If ratified, the deal would be the largest hostile takeover offer in the drug industry since the transaction creating Sanofi-Aventis in 2004. Sanofi-Synthelabo acquired Aventis for about $64 billion after raising its bid once. Sanofi’s offer expires December 10.

On September 15, Sanofi CEO Chris Viehbacher claimed at a press conference that investors who owned more than 50% indicated they were willing to sell their shares at “a reasonable price.”

Genzyme’s stock has sunk as much as 43% from its 2008 high after manufacturing glitches led to product shortages. This left the company vulnerable to a takeover.