April 27, 2017
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How Supplied


Didronel is indicated for the treatment of symptomatic Paget's disease of bone and in the prevention and treatment of heterotopic ossification following total hip replacement or due to spinal cord injury. Didronel is not approved for the treatment of osteoporosis.

Paget’s Disease

Didronel is indicated for the treatment of symptomatic Paget's disease of bone. Didronel therapy usually arrests or significantly impedes the disease process as evidenced by:

  • Symptomatic relief, including decreased pain and/or increased mobility (experienced by 3 out of 5 patients).
  • Reductions in serum alkaline phosphatase and urinary hydroxyproline levels (30 percent or more in 4 out of 5 patients).
  • Histomorphometry showing reduced numbers of osteoclasts and osteoblasts, and more lamellar bone formation.
  • Bone scans showing reduced radionuclide uptake at pagetic lesions.

In addition, reductions in pagetically elevated cardiac output and skin temperature have been observed in some patients.

In many patients, the disease process will be suppressed for a period of at least 1 year following cessation of therapy. The upper limit of this period has not been determined.

The effects of the Didronel treatment in patients with asymptomatic Paget's disease have not been studied. However, Didronel treatment of such patients may be warranted if extensive involvement threatens irreversible neurologic damage, major joints, or major weight-bearing bones.

Heterotopic Ossification

Didronel is indicated in the prevention and treatment of heterotopic ossification following total hip replacement or due to spinal cord injury.

Didronel reduces the incidence of clinically important heterotopic bone by about two-thirds. Among those patients who form heterotopic bone, Didronel retards the progression of immature lesions and reduces the severity by at least half. Follow-up data (at least 9 months posttherapy) suggest these benefits persist.

In total hip replacement patients, Didronel does not promote loosening of the prosthesis or impede trochanteric reattachment.

In spinal cord injury patients, Didronel does not inhibit fracture healing or stabilization of the spine.


Didronel should be taken as a single, oral dose. As with other bisphosphonates, it is recommended that Didronel should be swallowed with a full glass of water (6 to 8 oz). Patients should not lie down after taking the medication. However, should gastrointestinal discomfort occur, the dose may be divided. To maximize absorption, patients should avoid taking the following items within two hours of dosing:

  • Food, especially food high in calcium, such as milk or milk products.
  • Vitamins with mineral supplements or antacids which are high in metals such as calcium, iron, magnesium, or aluminum.

Paget’s Disease

Initial Treatment Regimens

5 to 10 mg/kg/day, not to exceed 6 months, or 11 to 20 mg/kg/day, not to exceed 3 months.

The recommended initial dose is 5 mg/kg/day for a period not to exceed 6 months. Doses above 10 mg/kg/day should be reserved for when 1) lower doses are ineffective or 2) there is an overriding need to suppress rapid bone turnover (especially when irreversible neurologic damage is possible) or reduce elevated cardiac output. Doses in excess of 20 mg/kg/day are not recommended.

Retreatment Guidelines

Retreatment should be initiated only after 1) a Didronel-free period of at least 90 days and 2) there is biochemical, symptomatic or other evidence of active disease process. It is advisable to monitor patients every 3 to 6 months although some patients may go drug free for extended periods. Retreatment regimens are the same as for initial treatment. For most patients the original dose will be adequate for retreatment. If not, consideration should be given to increasing the dose within the recommended guidelines.

Heterotopic Ossification

  • The following treatment regimens have been shown to be effective:
  • Total Hip Replacement Patients: 20 mg/kg/day for 1 month before and 3 months after surgery (4 months total).

Spinal Cord Injured Patients: 20 mg/kg/day for 2 weeks followed by 10 mg/kg/day for 10 weeks (12 weeks total). Didronel therapy should begin as soon as medically feasible following the injury, preferably prior to evidence of heterotopic ossification.

Retreatment has not been studied.


Didronel® (etidronate disodium) is available as 400 mg, white, scored, capsule-shaped tablets with “N|E” on one face and “406” on the other.

NDC 0430-0406-20 Bottles of 60 tablets

Store at 25°C (77°F); excursions permitted to 15 to 30° C (59 to 86° F) [see USP Controlled Room Temperature]

Manufactured by: Norwich Pharmaceuticals, Inc. North Norwich, NY 13814. Marketed by: Warner Chilcott (US), LLC Rockaway, NJ 07866. 1-800-521-8813. Revised: March 2015

This monograph has been modified to include the generic and brand name in many instances.

Last reviewed on RxList: 4/13/2015

How Supplied

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