Alendronate (Fosamax, Merck) is a bisphosphonate drug used for osteoporosis and several other bone diseases. It is marketed alone as well as in combination with vitamin D (2,800 U and 5600 U, under the name Fosamax+D). Merck's U.S. patent on alendronate is set to expire in 2008 and Merck has lost a series of appeals to block a generic version of the drug from being certified by the U.S. Food and Drug Administration.

On February 6, 2008, the US FDA approved the first generic versions of alendronate, which are being marketed by Barr Pharmaceuticals and Teva Pharmaceuticals USA. Teva Pharmaceuticals will make generic alendronate in 5-milligram, 10-milligram, and 40-milligram daily doses, and in 35-milligram and 70-milligram weekly doses, while Barr will make generic alendronate in 70-milligram tablets, which are taken once a week. Teva and Barr have already begun shipping their generic versions of alendronate to stores.