This excerpt taken from the SNY 20-F filed Apr 11, 2005.
Options to purchase Group shares
In conjunction with the acquisition of Synthélabo by Sanofi in 1999, Sanofi assumed stock option plans initiated by Synthélabo. The options were adjusted by the exchange ratio specified in the transaction but otherwise retained the same terms as those contained in the original Synthélabo Group options. No additional options will be granted under any of the assumed stock option plans.