Bisphosphonates

Question 1

Give some examples

Answer 1

Alendronate

Alendronic acid

Question 2

What are the indications for use

Answer 2

• 1st line Tx for pt at risk of osteoporosis fragility fractures
• Tx severe hypercalcaemia of malignancy
• Myeloma + breast cancer with bone mets (reduce risk of fractures cord compression, surgery)
• Paget’s disease - reduce bone turnover + pain

Question 3

What is the mechanism of action

Answer 3

• Reduce bone turnover by inhibiting action of osteoclasts (responsible for bone resorption)
• Similar structure to naturally occurring pyrophosphate –> readily incorporated
• Accumulate in osteoclasts where they inhibit activity + promote apoptosis
• net effect = reduction in bone loss + improvement in bone mass

Question 4

What are the side effects of bisphosphonates

Answer 4

• Oesophagitis (when taken orally)
• Hypophosphataemia
• jaw osteonecrosis
• Atypical femoral fracture

Question 5

What contra-indications are there

Answer 5

• Severe renal impairment
• Hypocalcaemia
• Upper GI disorders (risk of osteonecrosis)
• Smokers
• Dental disease

Question 6

What are the interactions

Answer 6

• Ca SALTS (inc milk, reduced absorption)
  Antacids
  Iron salts

Question 7

What to tell patient

Answer 7

remain upright for 30mins after taking medication