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MUSCULO-SKELETAL SYSTEM › DRUGS FOR TREATMENT OF BONE DISEASES › DRUGS AFFECTING BONE STRUCTURE AND MINERALIZATION › Bisphosphonates
etidronic acid
M05BA01
Forms & Strengths
- Oral tablet: 200 mg
- Oral tablet: 400 mg
Adult Dosing
- Paget's disease: 5 to 10 mg/kg/day orally for up to 6 months, or up to 20 mg/kg/day for up to 3 months
- Heterotopic ossification (spinal cord injury): 20 mg/kg/day for 2 weeks, then 10 mg/kg/day for 10 weeks
- Heterotopic ossification (total hip replacement): 20 mg/kg/day for 1 month preoperatively, then 20 mg/kg/day for 3 months postoperatively
Pediatric Dosing
- Safety and efficacy in pediatric patients have not been established
Indications
- Treatment of symptomatic Paget's disease of bone
- Prevention and treatment of heterotopic ossification following total hip replacement or spinal cord injury
Mechanism of Action
- First-generation bisphosphonate that binds to hydroxyapatite crystals in bone
- Inhibits osteoclast-mediated bone resorption and bone turnover
- At high doses, can inhibit bone mineralization (osteomalacia/Rickets-like effects)
Contraindications
- Hypersensitivity to etidronate or other bisphosphonates
- Active upper gastrointestinal abnormalities (e.g., stricture, dysphagia)
- Inability to stand or sit upright for at least 30 minutes
- Hypocalcemia
- Severe renal impairment (CrCl < 30 mL/min)
Adverse Reactions
- Nausea, diarrhea, abdominal pain
- Bone pain (typically transient, associated with Paget's disease treatment)
- Increased risk of fractures at high doses due to impaired mineralization
- Atypical femoral fractures
- Osteonecrosis of the jaw (rare)
Drug Interactions
- Calcium supplements, antacids, and iron reduce the gastrointestinal absorption of etidronate
- Aminoglycosides may increase the risk of hypocalcemia due to additive effects on serum calcium
- NSAIDs may increase the risk of gastrointestinal ulceration
Curated Content: Needs Vetting Before Put to Clinical Use