Romosozumab – New Drug for Osteoporosis

Medications used to treat osteoporosis are either antiresorptive, acting on osteoclasts or increase bone density by acting on osteoblasts.  Romosozumab has been approved by FDA for the treatment of post-menopausal women in April 2019 (1). This drug is a monoclonal antibody that binds with and inhibits sclerostin. It has a dual mode of action, increasing bone formation by osteoblastic activity and decreasing bone resorption by its action on osteoclasts (2).

Sclerostin is a small protein expressed by the SOST gene in osteocytes, bone cells that respond to mechanical stress applied to the skeleton and appear to play an important role in the regulation of bone remodeling. When sclerostin binds to its receptors on the cell surface of osteoblasts, a downstream cascade of intracellular signaling is initiated, with the ultimate effect of inhibiting osteoblastic bone formation (3).


The image is showing effects of sclerostin on bone (Image source).

Romosozumab may increase the risk of cardiovascular problems including heart attack and stroke (1). Therefore patient selection for this treatment is very important. Patients with past history of cardiovascular diseases should not be prescribed this drug. Even if there is no such history, it is advisable to investigate and exclude such conditions.

Two clinical trials were conducted to evaluate efficacy and safety of romosozumab. In one study this drug was given for one year. Vertebral fracture risk reduction was 73%, which continued in second year with treatment using denosumab against placebo.

In another study romosozumab was again used for one year and followed next year by alendronate. In this group vertebral fracture risk reduction was 50% which continued to second year with alendronate.

Patients having osteopenia or osteoporosis should be encouraged to take preventive measures. These include exercise, sunlight exposure, calcium intake, vitamin-D intake and healthy diet.

The best diagnostic test for osteoporosis is DEXA scan. It is recommended to repeat the scan yearly to see the effects of medical treatment.

References

(1) https://www.fda.gov/news-events/press-announcements/fda-approves-new-treatment-osteoporosis-postmenopausal-women-high-risk-fracture

(2) https://www.medscape.com/answers/330598-83112/what-is-the-role-of-romosozumab-in-the-treatment-of-osteoporosis

(3) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3956136/

(4) https://jme.bioscientifica.com/view/journals/jme/62/2/JME-18-0176.xml

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