Forteo®, Tymlos® and Evenity®: How Much Do They Really Reduce Fracture Risk?

The latest crop of recent bone drugs contains new anabolic drugs that enhance bone density. These drugs are designed to build new bone, while the older bisphosphonate bone drugs at best can only halt bone loss. Patients are told just that—that these new anabolic treatments will increase their bone density and also decrease fracture risk. Given the magnitude of this claim, I felt compelled to take a closer look at these medications to try to understand them a little better by asking the crucial question “How much do these new drugs really reduce fracture risk?” 

The following are the three anabolic bone–density-building drugs widely used today:  

• Forteo®  (teriparatide) 
• Tymlos®  (abaloparatide) 
• Evenity®  (romosozumab) 

All three drugs have five things in common: 

1. They temporarily increase bone density substantially, at times by 10% or more. 
2. However, any bone density gains that occur from the use of these drugs will be lost once the patient stops using the drug. Thus, upon stopping these new bone–density–building drugs, the patient must take one of the older bone drugs known to reduce bone breakdown (like Fosamax® or Prolia®). If they do not, then all bone density gains will be lost within a few years. 
3. All 3 drugs carry “Black Box” warnings: Tymlos® and Forteo® for bone cancer risk and Evenity® for cardiovascular disease. 
4. Each one can only be taken for up to 2 years, due to the Black Box warning of potentially life-threatening side effects. 
5. Each of these new bone drugs is inordinately expensive. My local pharmacy gave me their costs without insurance:
   Tymlos®$31,140.00 per year
   Forteo®$56,988.00 per year
   Evenity®$28,896.00 per year 

The Critical Question: 

How much do these new drugs really reduce fracture risk? 

The answer is not very much according to a new 2019 meta-analysis of 16 different large clinical trials involving nearly 19,000 patients. Looking at the large clinical trials on these three drugs, the authors reported that: 

• These drugs did not significantly reduce the risk of non-vertebral fractures (fractures of the hips, pelvis, or other parts of the body).  
• Each of these bone–density-building drugs did “significantly” reduce the risk of vertebral fractures, but when you look carefully at each individual study, you find that the actual, absolute reduction in risk of vertebral fracture was only 1 to 4%. In other words, 100 people had to be treated with these expensive and risky bone–density–building drugs to prevent between one and four fractures. 

If you want to read more on Forteo®, Tymlos®, or Evenity®, click the links to more studies. 

Until recently, the major bone drugs were bisphosphonates, such as Fosamax®, Boniva®, Actonel® or Reclast®. These older bone drugs were only able to halt bone loss; they did not build new bone. The three new anabolic drugs discussed in this blog, each in their own way, trick the body into building new bone. But all gains are lost when the drugs are stopped. Thus, the recommendation is that they are followed up with the old drugs to halt any further bone loss. 

If you are thinking about taking these new “bone-building” drugs, there are two key things to keep in mind: 

1. These new drugs by themselves reduce fracture by only a small percentage.  
2. To maintain any of the bone density gains made, and hopefully to reduce fracture risk, you will need to take one of the older bone-halting drugs like Fosamax®, Reclast® or Prolia®, probably for the rest of your life.