Many insurers won’t pay for TYMLOS unless you do step therapy. Which means did you try this, and it didn’t work, and then you tried the next drug , and it didn’t work so then your last drug option (TYMLOS) (because you tried step 1 and 2) and a bone building drug such as TYMLOS is deemed medically necessary by your doctor. And then it has to be on the DRUG Formulary. I ran into this problem. I was prescribed TYMLOS and then got a letter of denial because I didn’t try and fail teriparatide (the generic form of Forteo).