Last updated: October 17, 2014
Trade Names: Didronel
Synonyms: Disodium etidronate, sodium etidronate
Drug Class: Bisphosphonate
Tablets: 200- and 400 mg
Newer bisphosphonates are preferred (see Comments)
Paget’s disease: initially 5 mg/kg/day orally not to exceed 6 months
Heterotopic ossification with total hip replacement: 20 mg/kg/day for 1 month before and 3 months after surgery (4 months total)
Indications: Paget’s disease, prevention and treatment of heterotopic ossification (e.g., calcification after hip replacement)
Mechanism of Action: Adsorbs onto hydroxyapatite crystals and blocks their aggregation and growth
Contraindications: Hypersensitivity to bisphosphonates; severe renal impairment; osteomalacia; severe esophageal abnormalities, pregnancy
Precautions: Reduce dose in mild renal impairment. Avoid if possible if esophageal problems or renal impairment are present. Ensure that patient understands how the drug should be taken. A dental exam and preventive dental work should be performed before starting chronic bisphosphonate therapy. Paget’s disease with lytic lesions have a risk of fracture.
Monitoring: In Paget’s disease, alkaline phosphatase and markers of bone turnover are monitored as measures of response to treatment.
Pregnancy Risk: C
Common: Mild GI disturbance (i.e., nausea, dyspepsia, dysphagia), hypocalcemia (transient, mild), headache, increased bone pain in Paget’s
Less common: Severe erosive esophagitis, osteomalacia, osteonecrosis of the jaw, severe musculoskeletal pain, uveitis, altered taste, allergy
Antacids: Decreased bioavailability of etidronate
Calcium: If taken together, decreased bioavailability of etidronate
Patient Instructions: Take on an empty stomach (2 hours before meals). Should be taken with a full glass of water on arising in the morning. Nothing other than water should be taken for at least 30 minutes. Even coffee or fruit juice markedly reduce absorption. Delaying such intake for longer than 30 minutes (1–2 hours if possible) maximizes absorption. After taking, the patient must remain upright to reduce risk of esophageal irritation. Any other medications must be taken at least 30 minutes after bisphosphonate. Supplement calcium and vitamin D intake if required.
Comments: Etidronate should not be used for treatment of osteoporosis. Newer bisphosphonates are preferred for treatment of Paget’s as they are more potent and less likely to cause osteomalacia. Supplemental calcium and vitamin D are usually co-administered.
Clinical Pharmacology: Absorption 1%–5%; no metabolism; renal excretion. Half of absorbed dose is eliminated in 24 hours; the rest binds to calcium phosphate surfaces and is eliminated over months to years.
Ralston SH. Clinical practice. Paget's disease of bone. N Engl J Med 2013;368:644-50. PMID: 23406029