An Overview of Common Drugs Used in Osteoporosis

• Osteoporosis is a condition in which bones become weak and prone to fractures, commonly affecting women during menopause but also occurring in men due to hormonal disorders. 
• Treatment for osteoporosis involves a combination of lifestyle changes, including increased calcium and vitamin D intake, and pharmacological therapy with osteoporosis drugs such as bisphosphonates, selective estrogen receptor modulators, parathyroid hormone, calcitonin, monoclonal antibodies, and sclerostin inhibitors. 
• Each of these drugs works through different mechanisms to improve bone density and strength, but they may also cause various side effects, making it essential for patients to follow prescribed dosages and consult with their healthcare provider if they experience adverse effects. 

Osteoporosis is a prevalent and debilitating condition characterized by weakened bones, making individuals more susceptible to fractures. Although it is more common in women during the menopausal or perimenopausal stages, men can also be affected due to hormonal imbalances or other factors.  

Appropriate treatment and management of osteoporosis involve a combination of lifestyle changes and pharmacological therapy.  

This article discusses the various osteoporosis drugs, their mechanisms of action, dosages, and potential side effects. 

Introduction

In osteoporosis, the bone mineral density (BMD) is reduced, bone microarchitecture is disrupted, and the amount and various proteins in bone are altered.  

You must ask the patient with osteoporosis to increase their daily calcium and vitamin D intake from natural sources. However, along with that, they may require pharmacological therapy, such as: 

• Bisphosphonates 
• Selective estrogen receptor modulator (SERM) 
• Parathyroid hormone (PTH) 
• Calcitonin 
• Monoclonal antibodies 
• Sclerostin Inhibitor  

Here we will talk about the pharmacology of  osteoporosis drugs. 

Bisphosphonates

Bisphosphonates work by inhibiting bone resorption by exerting actions on osteoclasts or osteoclast precursors. They decrease the rate of bone resorption, leading to an increase in bone mineral density.  

It includes drugs such as: 

• Alendronate 
• Ibandronate 
• Risedronate 
• Zoledronic acid 

Alendronate 

• Sold under the brand name Binosto and Fosamax 
• Available as 5 mg, 10 mg, 35 mg, 40 mg, 70 mg tablets, and 70 mg/75 mL solution 
• The dose for preventive measures is 5 mg/day or 35 mg/week and for treatment is 10 mg/day or 70 mg/week. 

Ibandronate 

• Sold under the brand name Boniva
• Available as a 150 mg tablet and 1 mg/ml injection 
• The dose for prevention and treatment in the tablet dosage form is 150 mg/month. Through an intravenous route, its dose for osteoporosis treatment is 3mg/3 months.  

Risedronate 

• Sold under the brand name Actonel 
• Available as 5 mg, 30 mg, 35 mg, 150 mg tablets, and a delayed-release tablet formulation as 35 mg 
• The dose for prevention and treatment is 5 mg/day, 35 mg/week, or 150 mg/month. 

Zoledronic acid 

• Sold under the name Reclast 
• Available as a 5 mg injection 
• IV prevention dose is 5 mg every 2 years, and treatment is 5 mg yearly. 

The side effects of bisphosphonates are: 

• Hypocalcemia 
• May cause jaw osteonecrosis  
• GI adverse effects such as heartburn, esophageal irritation, esophagitis, abdominal pain, diarrhea 
• Bone, joint, or muscle pain 
• With IV administration, acute-phase reactions can occur, causing low-grade fever, myalgia, and arthralgia. It happens within 1 to 3 days of the infusion. 

Selective Estrogen Receptor Modulators

SERM is effective in osteoporosis because they decrease bone resorption and increase bone mineral density, hence lowering the incidence of fractures. 

Some examples include: 

Raloxifene 

• Sold under the brand name Evista 
• Available as a 60 mg tablet  
• For prevention and treatment, its dose is 60 mg/day 

The side effects of SERMs are: 

• Leg cramps 
• Hot flashes 
• Increased risk of thromboembolic events and stroke 

Parathyroid Hormones

The parathyroid hormone show effects in osteoporosis by: 

• Stimulating osteoblast function 
• Increasing gastrointestinal calcium absorption 
• Increasing renal tubular reabsorption of calcium 

That increases bone mineral density, bone mass, and strength, resulting in a decrease in osteoporosis-related fractures. 

Some examples include: 

• Abaloparatide 
• Teriparatide 

Abaloparatide 

 Sold under the brand name Tymos 

• Available as a 2,000 mcg/mL injection and prefilled pen that delivers 80 mcg/dose 
• The treatment dose is 80 mcg subcutaneously once daily. 

Teriparatide 

• Sold under the brand name Forteo 
• Available as a 250 mcg/mL injection, the syringe delivers a 20 mcg/dose 
• The treatment dose is 20 mcg subcutaneously once daily 

The side effects of parathyroid hormones are: 

• Muscle cramps 
• Injection site reactions 
• Tachycardia 
• Hypotension 
• Increased serum uric acid concentration 
• Hypercalciuria 
• Dizziness and nausea 
• Headache 
• Hypercalcemia 

Calcitonin

Calcitonin works by inhibiting bone resorption. However, its efficacy is not observed in early postmenopausal women. It is used in women with osteoporosis who are at least 5 years beyond menopause. 

• Sold under the brand name Miacalcin or Fortical 
• Available as a Miacalcin injection of 200 units/ml, Fortical and Miacalcin nasal spray as 200 units/actuation 
• The treatment dose is IM or subcutaneous 100 units every other day or nasal 200 units in 1 nostril daily. 

The side effects of calcitonin are: 

• Rhinitis 
• Local nasal irritation 

The injection may cause; 

• Nausea 
• Local inflammation 
• Flushing of face and hands 

Monoclonal Antibody

Monoclonal antibodies work by inhibiting the RANK ligand—a cytokine member of the tumor necrosis factor family. That inhibits osteoclast formation, function, and survival. Hence decreasing bone resorption and increasing bone mass and strength in cortical and trabecular bone. 

An example of a monoclonal antibody RANKL inhibitor is: 

Denosumab 

• Sold under the brand name Prolia  
• Available as a 60 mg/ml injection 
• The dose is subcutaneous 60 mg once every 6 months. 

The side effects of denosumab are: 

• Dermatitis 
• Rash 
• Eczema 
• Hypocalcemia 
• Rarely it may cause jaw osteonecrosis  

Sclerostin Inhibitor

Sclerostin is an osteocyte-derived glycoprotein that inhibits bone formation. Its inhibition causes osteoblast activity and bone formation. That decreases bone resorption and increases mineral density.  

An example of a sclerostin inhibitor is: 

Romosozumab 

• Sold under the brand name Evenity  
• Available as injection 105 mg/1.17 mL syringe 
• The dose is subcutaneous 210 mg (2 injections) once every month for up to 12 doses 

The side effects of Romosozumab are: 

• Headache  
• Arthralgia 

The Bottom Line

The management of osteoporosis requires a multifaceted approach, including lifestyle modifications and pharmacological osteoporosis drugs. A wide range of medications is available to help improve bone density and reduce the risk of fractures.

As with any treatment, it is crucial for patients to adhere to their prescribed regimen and maintain open communication with their healthcare provider to optimize their bone health and overall well-being. 

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