What is the difference between actonel (risedronate) and fossamax?

Similar, but differ. Both are bisphosphonate drugs, taken orally, which decrease bone breakdown by osteoclast cells, and therefore increase bone density ;#40;a marker of bone strength;#41;. Different dosing, but can be weekly or monthly for either in osteoporosis. Were used in tumors in or to bone-now drugs mostly given IV for that. Fosamax (alendronate) stays in the system and bone longer; was thought to be more GI irritating ;#40;maybe not;#41;.