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Bisphosphonates
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- 1Give eg's of & indications for bisphosphonates.eg's: alendronic acid, disodium pamidronate, zoledronic acid
Indications:
• Pt's at risk of osteoporotic fragility #'s - 1st line drug Rx
• Severe hypercalcaemia of malignancy - pamidronate & zoledronic acid
• Metastases in breast CA & myeloma - pamidronate & zoledronic acid reduce risk of #'s, cord compression, & the need for radiotherapy or Sx
• Paget's disease - 1st line Rx to reduce bone turnover & P - 2MOA of bisphosphonates.Bisphosphonates reduce bone turnover by inhibiting the action of osteoclasts, the cells responsible for bone resorption. Bisphosphonates have a similar structure to naturally occurring pyrophosphate, hence are readily incorporated into bone. As bone is resorbed, bisphosphonates accumulate in osteoclasts, where they inhibit activity and promote apoptosis. The net effect is reduction in bone loss and improvement in bone mass.
- 3SE's of bisphosphonates.• Oesophagitis - when taken orally
• Hypophophataemia
• Osteonecrosis of the jaw - rare, more likely with high dose IV
• Atypical femoral # - rare, usually in chronic treatment - 4CI's, cautions, & important interactions of bisphosphonates.CI's:
• Severe renal impairment
• Hypocalcaemia
• Upper GI disorders
Cautions:
• Smokers & pt's with major dental DS - due to jaw osteonecrosis
Important interactions:
Bisphosphonates bind calcium. Their absorption is therefore reduced if taken with calcium salts (including milk), as well as antacids & iron salts.