Teriparatide Treatment for Osteoporosis (Forteo and Tymlos)

Teriparatide is a relatively new medication for the treatment of osteoporosis.  It is recombinant human parathyroid hormone, which is a synthetic analog for human parathyroid hormone. It is the first medicine to treat osteoporosis by stimulating new bone growth.  Under the brand name Forteo it is targeted towards people with osteoporosis resulting from long-term glucocorticoid steroid use, such as prednisone.  Under the brand name Tymlos it is targeted at treating osteoporosis in post-menopausal women.  Both drugs are administered as daily subcutaneous injections from a pre-loaded injection device (like an epi-pen but with multiple doses).  Both versions of the drug have a black box warning that they increase the risk of osteosarcoma (a kind of bone cancer) and further indicates that a patient should not use either of these drugs for more than a combined two years (two year maximum for both drugs together, not for each one separately).  The other significant side effects include elevated levels of calcium in the blood (called hypercalcemia) and the onset or worsening of Orthostatic Intolerance (a form of autonomic dysfunction in which a person has difficulty regulating their blood pressure when standing) so the drugs should be administered, at least at first, when the person is sitting or lying down.

The active ingredient is essentially the same (teriparatide for Forteo and abaloparatide for Tymlos) but the formulations are not exactly the same. Osteoporosis and spinal fracture is apparently more common among mast cell disease patients than the normal population, so the inactive ingredients may be more important to consider.

Inactive ingredients in Forteo: glacial acetic acid, sodium acetate (anhydrous), mannitol, metacresol, and water for injection. In addition, hydrochloric acid solution 10% and/or sodium hydroxide solution 10% may have been added to adjust the product to pH 4.

Inactive ingredients in Tymlos (per disposable, pre-loaded injection pen containing 30 doses): 5 mg phenol, 5.08 mg sodium acetate trihydrate, 6.38 mg acetic acid, and water for injection.  (From the package insert for Tymlos)

 
Forteo Medication Guide (from FDA)

Info from Medscape

Teriparatide in the management of osteoporosis
"fractures of the spine result in significant morbidity and are also associated with increased mortality compared with individuals without a fracture...  It is the first osteoporosis treatment that leads to the formation of new bone with architecture similar to normal bone. Intense efforts have been made to understand the effect of teriparatide on antiresorptive therapy and vice versa. Although these relationships are not completely understood, the results of recent studies allow clinicians to begin to optimize therapeutic gains in bone mineral density and improve anti-fracture efficacy."

Vertebral fractures account for approximately 45% of osteoporosis-related fractures, and have significant immediate and long-term complications such as pain, respiratory complications, loss of height, and loss of quality of life. Of those presenting with vertebral fractures, the risk of new vertebral and non-vertebral fracture increases 4- to 5-fold

Moreover, there is mounting evidence that vertebral fractures also increase mortality within 1 year of the fracture and this excess risk increases with time

Although low bone mineral density (BMD) is highly predictive of an increased risk of future fracture (WHO 1994), multiple factors are involved in estimating an individual’s risk including age, race, previous fracture, glucocorticoid use, gender, history of falling, hyperparathyroidism, and malabsorption syndromes.