Didronel

Generic Name: Disodium etidronate
Product Name: Didronel

Indication

Didronel is used for:

• Paget’s disease with symptoms when other therapy is not appropriate; bone formation in abnormal places (heterotopic ossification) due to spinal cord injury or as a complication of total hip replacement.
  

  Action

  Didronel acts primarily on bone. It inhibits either re-absorption of crystal or the growth of crystal. In addition to that, it may also directly affect metabolic processes in the cells. When given at daily doses of 10mg/kg/day or above, Didronel has been observed to cause increased phosphate levels in the blood (hyperphosphataemia). No adverse effects of Didronel-induced hyperphosphataemia have been found and this elevation has not been found to be an indication for discontinuing therapy.

  Dose advice

  Didronel comes in 60 tablets of 200mg (rectangular, white) Didronel should be taken as a single oral dose at bedtime, preferably on an empty stomach. Items to avoid within two hours of dosing:

• Food, especially those high in calcium, e.g. milk or milk products.
• Vitamins with mineral supplements or antacids which are high in metals e.g. calcium, iron, magnesium or aluminium.For the use in Paget’s disease:Initial treatment:
• The recommended starting dose for most patients is 5mg per day for each kg of body weight (i.e. 5mg/kg/day), for not more than a period of 6 months.
• Doses above 10mg/kg/day should be reserved for use when there is an increased requirement to suppress high bone turnover or when the patient requires prompt reduction of the amount of blood the heart pumps out (cardiac output), which can be markedly increased in Pagetâ??s disease.
• Doses above 10mg/dy/day should be used cautiously and should not exceed 3 months in duration.
• Doses more than 20mg/kg/day are not recommended.Retreatment (Paget’s disease):
• Retreatment should be undertaken only after at least 3 months of absence of drug, and after the disease becomes active again and the levels of the disease markers increase.
• Duration of retreatment should NOT exceed the maximum duration of the initial treatment. For the use in abnormal bone formation (heterotopic ossification) due to spinal cord injury:
• The recommended dose is 20mg/kg/day for 2 weeks followed by 10mg/kg/day for 10 weeks, with a total treatment period of 12 weeks.
• Treatment should be instituted as soon as medically feasible following the injury, preferably before any abnormal bone formation is shown on x-ray.For the use in abnormal bone formation as a result of total hip replacement:
• The recommended dose is 20mg/kg/day for 1 month before the operation followed by 20mg/kg/day for 3 months after the operation. The total treatment period is 4 months. Overdosage may result in decreases in calcium level in the blood, and vomiting in some patients.
  

  Schedule

  S4

  Common side effects

• Diarrhoea (10% at 5mg/kg/day, 20% at 20mg/kg/day) – can be reduced by dividing the dose
• Nausea
• Increased or recurrent bone pain at existing sites affected by Pagetâ??s disease, occurrence rises with higher doses
• Increased risk of fracture in Paget’s disease if taken at 20mg/kg/day for more than 3 months
  

  Uncommon side effects

• Hair loss
• Joint pain and inflammation
• Burning of the tongue
• Hypersensitivity: skin rashes, itching, exacerbation of asthma
• Loss of memory, confusion, depression, hallucinations
• Reduction of white cell count
  

  References

  1. MIMS Prescribing Information 2005 â?? Didronel
  2. Therapeutic Guidelines: Endocrinology. Therapeutic Guidelines Limited (April 2003)For further information talk to your doctor.