Hi MLT:  Here's what the FDA's "Office of Generic Drugs" say's about the strict guidelines and approval process a generic drug must meet before it's available to the public.

"Health professionals and consumers can be assured that FDA approved generic drugs have met the same rigid standards as the innovator drug. To gain FDA approval, a generic drug must:

• contain the same active ingredients as the innovator drug(inactive ingredients may vary)
• be identical in strength, dosage form, and route of administration
• have the same use indications
• be bioequivalent
• meet the same batch requirements for identity, strength, purity, and quality
• be manufactured under the same strict standards of FDA's good manufacturing practice regulations required for innovator products"

For more info on alendronate sodium (aka Fosamax) see the link above.  You can also search through the link for info on ingredients (active/inactive) using the active ingredient name (alendronate sodium) or the brand name.  I believe the last bulleted point answers your question about possible inactive ingredients.

Hope this helps...