Didronel

Action

Blocks calcium absorption, slowing bone metabolism and reducing bone resorption and formation

Availability

Tablets: 200 mg, 400 mg

Indications and dosages

➣ Paget's disease

Adults: 5 to 10 mg/kg P.O. daily as a single dose for up to 6 months, or 11 to 20 mg/kg P.O. daily for up to 3 months

➣ Heterotopic ossification after hip replacement

Adults: 20 mg/kg P.O. daily for 1 month before and 3 months after surgery

➣ Heterotopic ossification in spinal cord injury

Adults: Initially, 20 mg/kg P.O. daily for 2 weeks, decreased to 10 mg/kg P.O. daily for 10 weeks

Dosage adjustment

• Decreased glomerular filtration rate

Contraindications

• Hypersensitivity to drug or its components

• Abnormalities of esophagus, such as stricture or achalasia, that delay esophageal emptying

• Osteomalacia

Precautions

Use cautiously in:

• renal impairment, long bone fractures, active upper GI condition (such as Barrett's esophagus, dysphagia, other esophageal diseases, gastritis, duodenitis, or ulcers)

• pregnant or breastfeeding patients

• children (safety not established).

Administration

• Give with 6 to 8 oz of water 2 hours before first meal.

• Make sure patient doesn't eat for 2 hours after receiving dose.

• Know that therapy longer than 3 months is not recommended.

Adverse reactions

GI: nausea, constipation, stomatitis, diarrhea, esophageal irritation

Metabolic: hyperphosphatemia

Musculoskeletal: bone pain and tenderness, fractures, osteonecrosis of the jaw

Skin: rash

Interactions

Drug-drug. Warfarin: increased prothrombin time

Drug-diagnostic tests. Serum phosphorus: increased level

Patient monitoring

• Monitor fluid intake and output.

• Monitor patient for GI discomfort. Divide doses as needed to ease symptoms.

• Assess bowel pattern. If constipation occurs, increase fluids and administer stool softeners, as prescribed.

• Closely monitor renal function tests and serum phosphorus level.

Patient teaching

• Instruct patient to take drug first thing in morning on an empty stomach, with 6 to 8 oz of water only and to stay upright for at least 30 minutes afterward.

• Instruct patient not to take drug with food because of decreased drug absorption.

• Tell patient not to consume highcalcium products, such as milk or antacids, or vitamins and mineral supplements high in calcium, iron, magnesium, or aluminum, within 2 hours of taking dose.

See Tell patient to immediately discontinue drug and notify prescriber if severe chest pain, difficulty or painful swallowing, or new or worsening heartburn occurs.

• Advise patient to report bone pain or decreased range of motion.

• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs and tests mentioned above.