Bisphosphonates

Summary

Bisphosphonates are drugs that commonly end in the suffix -dronate, including alendronate, risedronate, ibandronate, and zoledronate. These drugs function as pyrophosphate analogs to inhibit the activity of osteoclasts and reduce bone resorption. This makes these drugs clinically useful for treating osteoporosis, Paget’s disease of bone, bone metastases of various cancers, and other osteoclast-induced diseases. Side effects of taking bisphosphonates include corrosive esophagitis and osteonecrosis of the jaw.

Key Points

• Bisphosphonates (--dronate)
  • Drug Names
    • Alendronate
    • Risedronate
      • Minimal gastrointestinal toxicity
    • Ibandronate
    • Zoledronate
  • Mechanism
    • Acts as Pyrophosphate analogs 
      • Attach to hydroxyapatite binding sites in bone → inhibits osteoclast activity (anti-resorptive therapy)
  • Clinical Use
    • Treats any bone disease of osteoclasts
      • Osteopenia/Osteoporosis 
        • Sometimes given to people on chronic corticosteroids to prevent osteoporosis
      • Paget disease of bone
      • Osteogenesis imperfecta
        • Brittle bone disease that results in bones that break very easily. (Script)
      • Metastatic bone disease
    • Treats Hypercalcemia
      • Via decreasing the release of calcium from bone
  • Adverse Effects
    • Causes Corrosive esophagitis 
      • Patients are advised to take bisphosphonates on an empty stomach with plenty of water (due to poor gastrointestinal absorption) and remain upright for 30 minutes to avoid esophagitis
      • Presentation includes heartburn, retrosternal pain, pain with swallowing, abdominal pain, and occasional hematemesis
    • Causes Osteonecrosis of jaw
    • Causes Atypical femoral stress features
    • Causes hypocalcemia