Etidronate disodium (oral)
Etidronate disodium (oral) (Didronel)
Etidronate
(eh-tih- DROH-nayt)
Pregnancy Category: B Didronel (Rx)
Etidronate disodium (parenteral)
Etidronate disodium (parenteral) (Didronel, Didronel IV)
Etidronate
(eh-tih- DROH-nayt)
Pregnancy Category: C Didronel IV (Rx)

Classification: Bone growth regulator, antihypercalcemic

Action/Kinetics: Slows bone metabolism, thereby decreasing bone resorption, bone turnover, and new bone formation; it also reduces bone vascularization. Renal tubular reabsorption of calcium is not affected. Absorption: Dose-dependent; after 24 hr, one-half of absorbed drug is excreted unchanged. Absorption is affected by food or preparations containing divalent ions. Onset: 1 month for Paget's disease and within 24 hr for hypercalcemia. The drug remaining in the body is adsorbed to bone, where therapeutic effects for Paget's disease persist 3-12 months after discontinuation of the drug. Plasma t 1/2: 6 hr; bone t 1/2: Over 90 days. Approximately 50% excreted unchanged in the urine; unabsorbed drug is excreted through the feces.

Uses: PO: Paget's disease (osteitis deformans), especially of the polyostotic type accompanied by pain and increased urine levels of hydroxyproline and serum alkaline phosphatase. Heterotopic ossification due to spinal cord injury or total hip replacement. Parenteral: Hypercalcemia of malignancy inadequately managed by dietary modification or oral hydration or which persists after adequate hydration is restored. Investigational: Postmenopausal osteoporosis and prevention of bone loss in early menopause.

Contraindications: Enterocolitis, fracture of long bones, hypercalcemia of hyperparathyroidism. Serum creatinine greater than 5 mg/dL.

Special Concerns: Use with caution in the presence of renal dysfunction, in active UGI problems, and during lactation. Safety and efficacy have not been established in children.

Side Effects: GI: Nausea, diarrhea, constipation, ulcerative stomatitis. Bones: Increased incidence of bone fractures and increased or recurrent bone pain. Drug should be discontinued if fracture occurs and not restarted until healing takes place. Allergy: Angioedema, rash, pruritus, urticaria. Electrolytes: Hypophosphatemia, hypomagnesemia. Miscellaneous: Metallic taste, chest pain, abnormal hepatic function, fever, fluid overload, dyspnea, convulsions. Symptoms of rachitic syndrome have been reported in children receiving 10 mg or more/kg daily for long periods (up to 1 year) to treat heterotopic ossification or soft tissue calcification.

Laboratory Test Alterations: Hypomagnesemia, hypophosphatemia.

Overdose Management: Symptoms: Following PO ingestion, hypocalcemia may occur. Rapid IV administration may cause renal insufficiency. Treatment: Gastric lavage following PO ingestion. Treat hypocalcemia by giving calcium IV.

Drug Interactions: Products containing calcium or other multivalent cations absorption of etidronate

How Supplied: Etidronate disodium (oral): Tablet: 200 mg, 400 mg. Etidronate disodium (parenteral): Injection: 50 mg /mL

Dosage
?Tablets Paget's disease.
Adults, initial: 5-10 mg/kg/day for 6 months or less; or, 11-20 mg/kg for a maximum of 3 months. Reserve doses above 10 mg/kg when lower doses are ineffective, when there is a need for suppression of increased bone turnover, or when a prompt decrease in CO is needed. Do not exceed doses of 20 mg/kg/day. Another course of therapy may be instituted after rest period of 3 months if there is evidence of active disease process. Monitor every 3 to 6 months.
Heterotopic ossification due to spinal cord injury.
Adults: 20 mg/kg/day for 2 weeks; then 10 mg/kg/day for 10 weeks. Treatment should be initiated as soon as possible after the injury, preferably before evidence of heterotopic ossification.
Heterotopic ossification complicating total hip replacement.
Adults: 20 mg/kg/day for 30 days preoperatively; then, 20 mg/kg/day for 90 days postoperatively.
?IV Infusion Hypercalcemia due to malignancy.
7.5 mg/kg/day for 3 successive days. If necessary, a second course of treatment may be instituted after a 7-day rest period. The safety and effectiveness of more than two courses of therapy has not been determined. Reduce the dose in those with renal impairment. Etidronate tablets may be started the day after the last infusion at a dose of 20 mg/kg/day for 30 days (treatment may be extended to 90 days if serum calcium levels are normal). Use for more than 90 days is not recommended.