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Etidronate Disodium

Pronunciation: e-ti-DROE-nate dye-SOE-dee-um
Class: Bisphosphonate

Trade Names

Didronel
- Tablets 400 mg

Etidronate Disodium
- Tablets 200 mg
- Tablets 400 mg

CO Etidronate (Canada)
Gen-Etidronate (Canada)

Pharmacology

Inhibits normal and abnormal bone resorption; reduces bone formation.

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Pharmacokinetics

Absorption

Approximately 3% is absorbed.

Distribution

Approximately 50% of the absorbed dose is distributed to bone compartments. Does not cross blood-brain barrier.

Metabolism

Not metabolized.

Elimination

The plasma half-life is 1 to 6 h. In animals, bone Cl is 165 days. Unabsorbed drug is excreted in feces. Approximately 50% of the absorbed dose is excreted in the urine within 24 h.

Indications and Usage

Treatment of symptomatic Paget disease of bone; prevention and treatment of heterotopic ossification following total hip replacement or caused by spinal cord injury.

Unlabeled Uses

Prevention and treatment of corticosteroid-induced osteoporosis; prevention of osteoporosis in spinal cord injury patients.

Contraindications

Hypersensitivity to etidronate; clinically overt osteomalacia; abnormalities of the esophagus that delay esophageal emptying (eg, stricture, achalasia).

Dosage and Administration

Heterotopic Ossification Following Total Hip Replacement
Adults

PO 20 mg/kg/day for 1 mo preoperatively followed by 20 mg/kg/day for 3 mo postoperatively.

Heterotopic Ossification From Spinal Cord Injury
Adults

PO 20 mg/kg/day for 2 wk followed by 10 mg/kg/day for 10 wk; total treatment period is 12 wk.

Paget Disease
Adults

PO Initial treatment is 5 to 10 mg/kg/day (not to exceed 6 mo) or 11 to 20 mg/kg/day (not to exceed 3 mo). Reserve dosages greater than 10 mg/kg/day for specific situations. Max dosage is 20 mg/kg/day. For re-treatment, initiate only after etidronate-free period of at least 90 days and if there is evidence of active disease.

General Advice

  • Administer prescribed dose on an empty stomach at least 2 h before or after food, especially items high in calcium; vitamins with minerals; or antacids high in calcium, iron, magnesium, or aluminum.
  • Administer as a single oral dose; may administer in divided doses if GI side effects (eg, nausea, diarrhea) are bothersome.
  • Have patient swallow tablet(s) whole with a full glass (6 to 8 oz) of plain water and remain upright after taking medication.

Storage/Stability

Store tablets between 59° and 86°F and away from excessive heat (over 104°F).

Drug Interactions

Aluminum, calcium, iron, magnesium, other cations

Etidronate absorption may be decreased. Do not administer etidronate within 2 h before or after these agents.

Chemotherapy, corticosteroids (eg, prednisolone)

The risk of osteonecrosis of the jaw may be increased. Monitor the patient.

Food

Absorption of etidronate is decreased by food. To maximize absorption, do not take etidronate within 2 hours before or after a meal.

Warfarin

There have been isolated reports of patients experiencing increases in their PT when etidronate was added to warfarin therapy. The majority of these reports involved variable PT elevations without clinically important sequelae. Monitor PT in patients receiving warfarin.

Adverse Reactions

CNS

Amnesia, confusion, depression, hallucination, headache, paresthesias (postmarketing).

Dermatologic

Alopecia, Stevens-Johnson syndrome (postmarketing).

GI

Diarrhea; nausea; esophagitis, gastritis, glossitis, exacerbation of peptic ulcer disease, perforation of peptic ulcer (postmarketing).

Genitourinary

Abnormal elevations of serum creatinine; mild to moderate abnormalities in renal function.

Hematologic

Agranulocytosis, pancytopenia, leukopenia (postmarketing).

Hypersensitivity

Angioedema, follicular eruption, macular and maculopapular rash, pruritus, urticaria (postmarketing).

Musculoskeletal

Arthropathies including arthralgia and arthritis, bone fracture, leg cramps, osteomalacia (postmarketing).

Respiratory

Exacerbation of asthma (postmarketing).

Miscellaneous

Increased or recurrent bone pain in Paget disease; hyperphosphatemia.

Precautions

Monitor

Monitor patients with Paget disease every 3 to 6 mo for re-treatment. Radiographically and biochemically monitor patients with predominantly lytic lesions to permit termination of etidronate in those patients unresponsive to treatment. Closely monitor patients with renal impairment. Monitor patients for signs and symptoms of incapacitating bone, joint, and/or muscle pain. Perform periodic dental exams for signs of osteonecrosis of the jaw.


Pregnancy

Category C .

Lactation

Undetermined.

Children

Safety and efficacy not established.

Elderly

Because elderly patients are more likely to have decreased renal function, take care when prescribing this drug therapy.

Renal Function

Dosage should be reduced when reduction in glomerular filtration rates are present.

Bone turnover

Etidronate suppresses bone turnover and may retard mineralization of osteoid laid down during bone accretion process.

Calcium/Vitamin D intake

Ensure that patient's daily calcium and vitamin D intake are evaluated before starting therapy, and that calcium and/or vitamin D supplementation is being used in patients with inadequate daily intake.

GI effects

May cause local irritation of the upper GI mucosa. Use this drug with caution in patients with active upper GI problems, such as dysphagia, symptomatic esophageal diseases, gastritis, duodenitis, or ulcers.

Musculoskeletal effects

Severe and occasionally incapacitating bone, joint, and/or muscle pain has been reported.

Osteomalacia/Bone fracture

In patients with Paget disease, treatment regimens exceeding the recommended daily maximum dose for periods of more than 6 mo may be associated with osteomalacia and an increased risk of fracture.

Osteonecrosis of the jaw

May occur spontaneously and is generally associated with tooth extraction and/or local infection with delayed healing. Risk factors include dental procedures, poor oral hygiene, and comorbid disorders (eg, preexisting dental disease, anemia, coagulopathy, infection, ill-fitting dentures).

Paget disease

Response may be slow and may continue for months after treatment has been discontinued. Dosage must not be prematurely increased or treatment prematurely reinitiated until patient has had at least a 90-day etidronate-free interval.

Overdosage

Symptoms

Diarrhea, fracture, hematologic abnormalities, hypocalcemia, nephritic syndrome, paresthesia of fingers, vomiting.

Patient Information

  • Advise patient to read patient package insert before starting therapy and to reread the insert each time the medication is renewed.
  • Advise patient to take tablets on an empty stomach, and to take 2 h before or after food, multivitamins with minerals, or antacids high in calcium, iron, magnesium, or aluminum.
  • Instruct patient to take each dose with 6 to 8 oz of plain water and not to lie down after taking a dose.
  • Instruct patient to discontinue therapy and seek medical care if any of the following occur: difficulty swallowing, new or worsening heartburn, pain behind breastbone.
  • Advise patient to maintain adequate intake of calcium and vitamin D with diet and/or supplements.
  • Advise women to notify health care provider if pregnant, planning to become pregnant, or breast-feeding.
  • Instruct patient not to take any prescription or OTC medications, herbal preparations, or dietary supplements unless advised by health care provider.
  • Advise patient that follow-up visits and laboratory tests may be required to monitor therapy and to keep appointments.

Copyright © 2009 Wolters Kluwer Health.

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