Alendronic acid (INN) or alendronate sodium (USAN) — sold as Fosamax by 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 IU and 5600 IU, under the name Fosamax+D). Merck`s U.S. patent on alendronate expired in 2008 and Merck lost a seri....