etidronate (Didronel)

Introduction

Tradename: Didronel.

Indications

• Paget's disease of the bone
  • 5-10 mg/kg/day, do not exceed 6 months
  • 11-20 mg/kg/day, do not exceed 3 months
• hypercalcemia of malignancy
  • 20 mg/kg/day for 30 days
  • continue for another 30 days if needed
• hypertrophic calcification secondary to spinal cord injury
  • 20 mg/kg/day for 2 weeks, then
  • 10 mg/kg/day for 10 weeks
• total hip replacement (complicated)
  • 20 mg/kg/day for 1 month preoperatively
  • 20 mg/kg/day for 3 months post-operatively
• osteoporosis: 400 mg PO QD for 2 weeks every 3 months
• hypercalcemia:
  • 7.5 mg/kg in 250 mL NS IV over 2 hours QD for 3 days
• doses > 20 mg/kg/day are not recommended

Dosage

Tabs: 200 & 400 mg

Pharmacokinetics

• oral bioavailability is low, take on empty stomach
• not metabolized

elimination via kidney

Adverse effects

• not common (1-10%)
  • fever
  • fluid overload
  • GI complaints
    • nausea, constipation, diarrhea, anorexia, dyspepsia, metallic taste
  • metabolic disturbances
    • hypomagnesemia, hypophosphatemia, elevated serum transaminases
  • bone pain
• uncommon (< 1%)
  • occult fecal blood, increased risk of fractures, renal impairment, hypersensitivity, angioedema (rare), convulsions (rare), rash

• drug adverse effects of bisphosphonates

Drug interactions

• Ca+2 & antacids interfere with absorption

• drug interaction(s) of bisphosphonates with proton pump inhibitors
• drug interaction(s) of bisphosphonate with Ca+2

Mechanism of action

• bisphosphonate
• acts primarily on bone to inhibit resorption
• inhibits osteoclastic activity

More general terms

• bisphosphonate

Additional terms

• hypercalcemia
• osteoporosis

Database

• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=23894
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=3305
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=123827
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=17572
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=19629
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=26938