Bisphosphonates

Question 1

What Are Bisphosphonates and How Do They Work?

Answer 1

Bisphosphonates are drugs that reduce bone resorption by hindering the formation, recruitment and
function of osteoclasts. Most commonly in the management of osteoporosis, but are also used in the
management of many other non-malignant and malignant conditions.

Question 2

How can bisphosphonates lead to bisphosphonate-related ostonecrosis of the jaw (BONJ) ?

Answer 2

Bisphosphonates accumulate at sites of high bone turnover, such as in the jaw. This may reduce bone turnover and bone blood supply and lead to death of the bone, termed osteonecrosis.

Question 3

What is bisphosphonate-related osteonecrosis of the jaw (BONJ) ?

Answer 3

BONJ is defined as exposed, necrotic bone in the maxilla or mandible that has persisted for more than eight
weeks in patients taking bisphosphonates and where there has been no history of radiation therapy to the
jaw. Symptoms include delayed healing following a dental extraction or other oral surgery, pain, soft tissue
infection and swelling, numbness, paraesthesia or exposed bone.

Question 4

Why should’t bisphosphonates be discontunied prior to oral surgery ?

Answer 4

There is no supporting evidence that BONJ risk will be reduced if the patient temporarily, or even
permanently, stops taking bisphosphonates prior to invasive dental procedures since the drugs may
persist in the skeletal tissue for years. If a patient has taken bisphosphonates in the past but is no
longer taking them for whatever reason (i.e. completed or discontinued the course, taking a drug
holiday), allocate them to a risk group as if they are still taking them.

Question 5

Example of bisphosphonates and their indication.

Answer 5

alendronic acid Osteoporosis
zoledronic acid Paget’s disease
Skeletal events associated with bone metastases
Hypercalcaemia

risedronate sodium Osteoporosis
Paget’s disease

sodium clodronate Bone pain
Skeletal events associated with bone metastases
Hypercalcaemia

(TOP 3 MOST COMMONLY PRESCRIBED)

Question 6

Conditions that mey be treated with bisphosphonates (malignant, non-malignant) ?

Answer 6

Non-malignant Malignant
Osteoporosis Multiple myeloma
Paget’s disease Breast cancer
Osteogenesis imperfecta Prostate cancer
Fibrous dysplasia Bony metastatic lesions
Primary hyperparathyroidism Hypercalcemia Cystic fibrosis malignancy

Question 7

Incidence and risk of BONJ ?

Answer 7

The epidemiology of ONJ is currently unclear as it is an extremely rare condition. The incidence of ONJ in the
general population is unknown. Estimates of ONJ in patients taking bisphosphonates range from 1 in 10,000
to < 1 in 100,000 persons per years’ exposure.