Didronel, EHDP
Classifications: bisphosphonate; regulator, bone metabolism;
Therapeutic: bone metabolism regulator

Pregnancy Category: C


200 mg, 400 mg tablets


Diphosphate preparation with primary action on bone. Reduces elevated cardiac output associated with Paget's disease by decreasing vascularity of bone. Induces reversible hyperphosphatemia without adverse effects. Lowers serum alkaline phosphatase.

Therapeutic Effect

Slows rate of bone resorption and new bone formation in pagetic bone lesions and in normal remodeling process. Response of Paget's disease may be slow (1–3 mo) and may continue for months after treatment is discontinued.


Symptomatic Paget's disease and heterotopic ossification due to spinal cord injury or after total hip replacement.

Unlabeled Uses

Prevention and treatment of corticosteroid-induced osteoporosis.


Enterocolitis; pathologic fractures; renal failure; pregnancy (category C); lactation. Safety and effectiveness in children are not established.

Cautious Use

Renal impairment; asthma; colitis; dysphagia; esophagitis; gastritis; patients on restricted calcium and vitamin D intake.

Route & Dosage

Paget's Disease
Adult: PO 5–10 mg/kg/d for up to 6 mo or 11–20 mg/kg/d for up to 3 mo, may repeat after 3–6 mo off the drug if necessary

Heterotopic Ossification Due to Spinal Cord Injury
Adult: PO 20 mg/kg/d for 2 wk, then 10 mg/kg/d for an additional 10 wk

Heterotopic Ossification Due to Total Hip Arthroplasty
Adult: PO 20 mg/kg/d starting 1 mo before the procedure and continuing for 3 mo after


  • Give as single dose on empty stomach 2 h before meals with full glass of water or juice to reduce gastric irritation.
  • Relieve GI adverse effects by dividing total oral daily dose.

Adverse Effects (≥1%)

GI: Nausea, diarrhea, loose bowel movements, metallic or altered taste. Musculoskeletal: Increased or recurrent bone pain in pagetic sites, onset of bone pain in previously asymptomatic sites, increased risk of fractures in patient with Paget's disease. Metabolic: Hypocalcemia, hyperphosphatemia, elevated serum phosphatase, suppressed mineralization of uninvolved skeleton (focal osteomalacia). Urogenital: Renal insufficiency (high doses).


Drug: calcium supplements, antacids, iron and other mineral supplements may decrease absorption of etidronate (give etidronate 2 h before other drugs). Food: Food, especially milk and dairy products, will decrease absorption of etidronate (give 2 h before meals).


Absorption: Variably from GI tract. Distribution: 50% distributed to bone. Metabolism: Not metabolized. Elimination: 50% in urine. Half-Life: 6 h.

Nursing Implications

Assessment & Drug Effects

  • Report persistent nausea or diarrhea; GI adverse effects may interfere with adequate nutritional status and need to be treated promptly.
  • Monitor I&O ratio, serum creatinine, or BUN of patient with impaired kidney function.
  • Lab tests: Periodic serum calcium and phosphate.
  • Monitor for signs of hypocalcemia. Latent tetany (hypocalcemia) may be detected by Chvostek's and Trousseau's signs and a serum calcium value of 7–8 mg/dL.
  • Note: Serum phosphate levels generally return to normal 2–4 wk after medication is discontinued.

Patient & Family Education

  • Avoid eating 2 h before or after taking etidronate. Drug absorption is decreased by food, especially milk, milk products, and other foods high in calcium, mineral supplements, and antacids.
  • Notify physician promptly of sudden onset of unexplained pain. Risk of pathological fractures increases when daily dose of 20 mg/kg is taken longer than 3 mo.
  • Report promptly if bone pain, restricted mobility, heat over involved bone site occur.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

© 2006-2022 Last Updated On: 11/26/2022 (0)
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