eh-tih-DROE-nate

• Treatment of Paget’s disease of bone.
• Treatment and prophylaxis of heterotopic calcification associated with total hip replacement or spinal cord injury.

• Blocks the growth of calcium hydroxyapatite crystals by binding to calcium phosphate.

• Decreased bone resorption and turnover.

Absorption: Absorption is generally poor (1–6%) after oral administration.

Distribution: Half of the absorbed dose is bound to hydroxyapatite crystals in areas of increased osteogenesis.

Metabolism/Excretion: Unabsorbed drug is eliminated in the feces; 50% of the absorbed dose is excreted unchanged by the kidneys.

Half-life: 5–7 hr.

Contraindicated in:

• Hypersensitivity
• Overt osteomalacia
• Abnormalities of the esophagus which delay esophageal emptying (i.e. strictures, achalasia).

Use Cautiously in:

• History of upper GI disorders
• Hypocalcemia
• Hypovitaminosis D
• Renal impairment (dosage reduction may be needed)
• Invasive dental procedures, cancer, receiving chemotherapy, corticosteroids, or angiogenesis inhibitors, poor oral hygeine, periodontal disease, dental disease, anemia, coagulopathy, infection, or poorly-fitting dentures (may ↑ risk of jaw osteonecrosis)
• OB: Lactation: Pedi: Safety not established.

GI: diarrhea, nausea, esophagitis, esophageal cancer, esophageal ulcer.

MS: musculoskeletal pain, microfractures, osteonecrosis (primarily of jaw).

Derm: TOXIC EPIDERMAL NECROLYSIS.

Drug-Drug:

• Antacids, mineral supplements, or buffers (as in didanosine) containing calcium, aluminum, iron, or magnesium may ↓ absorption of etidronate.
• Hypocalcemic effect may be additive with calcitonin.

Drug-Food:

• Foods containing large amounts of calcium, aluminum, iron, or magnesium may ↓ absorption of etidronate.

Paget’s Disease

• PO (Adults): 5–10 mg/kg/day single dose for up to 6 mo or 11–20 mg/kg/day for not more than 3 mo.

Heterotopic Ossification (Hip Replacement)

• PO (Adults): 20 mg/kg/day for 1 mo before and 3 mo after surgery.

Heterotopic Ossification (Spinal Cord Injury)

• PO (Adults): 20 mg/kg/day for 2 wk, then decreased to 10 mg/kg/day for 10 wk.

• PO: Administer on empty stomach, because food decreases absorption. Swallow tablet whole; do not break, crush, or chew.

Didronel

Therapeutic Classification: bone resorption inhibitors, hypocalcemics

Pharmacologic Classification: biphosphonates

(Generic available)

• Tablets: 200 mg; 400 mg;

†As measured by decreased urinary hydroxyproline.

• Assess patient for bone pain, weakness, or loss of function before and throughout therapy. Bone pain may persist or increase in patients with Paget’s disease; usually subsides days to mo after therapy is discontinued. Confer with health care professional regarding analgesic to control pain.
• Perform a routine oral exam prior to initiation of therapy. Dental exam with appropriate preventative dentistry should be considered prior to therapy. Patients with history of tooth extraction, poor oral hygiene, gingival infections, diabetes, or use of a dental appliance or those taking immunosuppressive therapy, angiogenesis inhibitors, or systemic corticosteroids are at greater risk for osteonecrosis of the jaw.
• Heterotopic Ossification: Monitor for inflammation and pain at the site and loss of function if ossification occurs near a joint.

• Etidronate interferes with bone uptake of technetium 99 in diagnostic scans.
  • Paget’s disease:↓ urinary excretions of hydroxyproline and serum alkaline phosphatase are often the first clinical signs of effectiveness; monitor every 3 mo. Treatment is restarted when levels return to 75% of pretreatment values. Monitor serum phosphate levels before and 4 wk after beginning therapy. Dose may be ↓ if serum phosphate is ↑ without corresponding ↓ in urinary excretion of hydroxyproline or serum alkaline phosphatase.

• Acute pain (Indications, Side Effects).
• Risk for injury (Indications).

• Advise patient to take as directed. Take missed doses as soon as remembered unless almost time for next dose. Do not double up on doses. Dose should not be taken within 2 hr of eating (especially products high in calcium) or taking vitamins or antacids, because absorption will be impaired.
• Instruct patient to notify health care professional if swallowing difficulties, chest pain, new or worsening heartburn, or trouble or pain when swallowing occurs; may be signs of problems of the esophagus.
• Instruct patient to notify health care professional if diarrhea occurs. Health care professional may divide the dose throughout the day to control diarrhea.
• Encourage patients to comply with diet recommendations. Diet should contain adequate amounts of calcium and vitamin D (see Appendix M).
• Inform patient that severe musculoskeletal pain may occur within days, months, or yr after starting etidronate. Symptoms may resolve completely after discontinuation or slow or incomplete resolution may occur. Notify health care professional if severe pain occurs.
• Advise patient to notify health care professional if rash or signs and symptoms of osteonecrosis of the jaw (pain, numbness, swelling of or drainage from the jaw, mouth, or teeth) occur.
• Emphasize need for keeping follow-up appointments to monitor progress, even after medication is discontinued, to detect relapse.
• Advise patient to inform health care professional of etidronate therapy prior to dental surgery.
• Advise patient to notify health care professional if pregnancy is planned or suspected or if breastfeeding.

• Decreased bone pain and fractures in Paget’s disease.
• Prevention or treatment of heterotopic ossification. Normal serum calcium levels are usually attained in 2–8 days in hypercalcemia associated with bony metastasis. Therapy may be repeated once after 1 wk.

NDC Code^*

• 0378- Mylan Pharmaceuticals Inc.
  • 0378-3288- Etidronate Disodium
    • 0378-3288-91- 60 TABLET in 1 BOTTLE, PLASTIC (0378-3288-91)