@2024tymloshelp this is an interesting question because the most cited study advancing the theory that Fosamax is more effective used 70mg alendronate (Fosamax) and 35mg risidronate (Actonel) I've read that Actonel is more bioactive and that given in equal doses the effect is equal, but I can't find study sources. I have been told, by the endocrinologist I see, that Actonel adheres less tightly to the bone than Fosamax and so stays attached to your bone for fewer years, making it advantageous for following the bisphosphonate with an anabolic medication.