Bisphosphonates for osteoporosis
Medically Reviewed By : Dr K. Hari Chandana
MBBS, MS ORTHOPAEDICS
( Fellowship in Trauma, Fellowship in Pain Management )
Introduction
Bisphosphonates are the class of drugs that have been used for Osteoporosis for decades. They are proven to be effective in treating osteoporosis and prevention of fracture of bones.
Bisphosphonates are decades older drugs for osteoporosis, commonly used by physicians. They are called Bis or diphosphonates.
Osteoporosis is a disease of bones which weakens them to the extent that they are easily broken causing fractures and sometimes big joints causing the patient immobile.
Now, what exactly do normal bones function and how does it ends up in osteoporosis in only certain patients?
The answer is – Normal bones have a cycle of formation and resorption. There are two types of bone cells, osteoblasts which involve the formation of cells of new bone whereas osteoclasts help the resorption of bone means the death of old bone. When a patient suffers from osteoporosis, this mechanism is disturbed. The formation of new bone cells doesn’t take place, and old bone cells resorb, so the bone becomes porous and spongy.
Then what do bisphosphonates do?
Bisphosphonates are molecules which are very similar to the molecule present in the bone called pyrophosphate. Pyrophosphate molecule is resorbed by osteoclasts.
Bisphosphonates are very difficult for the osteoclasts to identify and resorb so this group of drugs helps in the late resorption of bone, resulting in the prevention and progression of osteoporosis. This establishes the fact that bisphosphonates are preventive medicines for osteoporosis
What are the benefits of taking bisphosphonates:
- Increased bone density: It has been seen that the bisphosphonates have proved to be effective for bone health increasing the bone mineral density thus making them stronger.
- Reduction of fracture risk: Bisphosphonates substantially reduce the risk of fractures particularly of hip bone, spine and other important skeletal structures.
Do bisphosphonates have serious side effects?
yes, it can have serious side effects but not in all patients The FDA has approved bisphosphonates for the treatment and prevention of osteoporosis.
What all common side effects constitute:
- Gastroesophageal reflux disease (GERD)
- Oesophagitis( inflammation of oesophagus)
- Gastritis( inflammation of stomach)
- Gastric ulcers ( ulcers in the stomach)
- Flu-like symptoms, fever, malaise (body ache), fatigue
- Headache
The above side effects can be treated with medications, and they resolve completely.
What are Some serious side effects of bisphosphonates:
- Uveitis( inflammation of the inner part of the eye)
- Conjunctivitis
- Osteonecrosis of the jaw (destruction of the jaw bone)
What are the conditions that Bisphosphonates treat other than osteoporosis?
- Postmenopausal women: In postmenopausal women because of lack of oestrogen calcium deficiency is seen which results in brittle bones
- Cancer: Multiple myeloma is cancer of bones in which cancerous plasma cells attack and replace healthy blood cells resulting in breaking of bones and pains
- Paget's disease: It is chronic disorder of bones that cause bones to grow longer but weaker.
- Steroid-induced osteoporosis: Side effect of corticosteroids is reducing the absorption of calcium and increasing bone loss causing osteoporosis.
- As a preventive measure to restrict osteoporosis: Bisphosphonates are known to suppress bone resorption and increase bone strength thus it can prevent osteoporosis.
- Hypercalcemia (excessive calcium in the blood) in cancer patients
- To prevent fractures in children and patients with long-standing illnesses who are prone to fracture
- Osteogenesis imperfecta (a genetic disease in which bones become brittle)
How to take bisphosphonates
- Consideration for use: Bisphosphonates treatment selection is done for certain types of patients. Health care professionals must consider the potential risk of fractures in the patients like postmenopausal women or men with significant history of fractures. Treatment initiation is done on the basis of fracture risk, medical history and comorbidities.
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Bisphosphonates for osteoporosis are either taken orally or intravenous. Bisphosphonate therapy is chosen depending on the patient's condition. Bisphosphonates usually take 6-12 months to work, and you might need to take it for 5 years orally or 3 years intravenously.
Oral Bisphosphonates:
- Alendronate
- Risedronate
Intravenous Bisphosphonates:
Pamidronate
- Zoledronic acid
They are taken on a daily, weekly or monthly or even yearly basis as prescribed by the doctor
Furthermore, your doctor will advise you to take a calcium-rich diet or calcium supplements, as well as Vitamin D supplements if you have Vitamin D deficiency.
Have you heard Bisphosphonates are taken in a sitting position?
Yes, you heard right. Bisphosphonates have a mode of action
So, the patient is instructed to take the oral tablet in an upright position in the morning on an empty stomach. Patient has to sit or stand upright for 30 to 60 minutes. Generally, no food or drink is allowed after taking a tablet for 30-60 minutes.
Why follow so many instructions to take a tablet?
You must be wondering, yes you have to follow the rules who are taking tablets orally.
As already discussed in the article earlier, bisphosphonates are well known to cause side effects like GERD (gastroesophageal reflux disease) and gastritis. To avoid side effects, you are instructed to follow rules and those who don’t comply, experience serious side effects.
- Oral bisphosphonates: alendronate and risedronate are two oral bisphosphonates which are generally given to patients having no history of gastric ulcer or oesophageal problems. It is given to patients who have these problems but controlled by regular medications. Both bisphosphonates are known to prevent vertebral and hip fracture in osteoporosis
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Intravenous bisphosphonates: Ibandronate and zoledronic acid are intravenous bisphosphonates. Bisphosphonates injections are infused in primary medical care settings for 15 minutes yearly or monthly as indicated. They are administered to the patients who can not tolerate oral bisphosphonates due to gastric or esophageal problems. They are well known to treat osteoporosis and prevent fractures in men and postmenopausal women.
Pamidronate is bisphosphonate used to treat hypercalcemia due to bone cancer conditions like multiple myeloma.
Etidronate is bisphosphonate. Etidronate is the drug of Choice in Paget's disease is a medical condition in which new bone formation is abnormal. The new bone is brittle and spongy. - Caution: Oral bisphosphonates should be discontinued as soon as the patient experiences side effects like upper GI ( gastro-intestinal) disease or oesophagitis. Intravenous or oral bisphosphonates are contra-indicated in chronic renal disease.
- Conclusion: Bisphosphonates no doubt have been widely used for bone loss and fracture risks. It has shown effectiveness in treatment and prevention of osteoporosis in men and women with a wide variety of causes. However, they may have serious side effects so it should be taken under medical supervision. It's important for the patient to know benefits and associated side effects of bisphosphonates before starting the treatment.