Ibandronate is an aminobisphosphonate that is a potent inhibitor of bone resorption. It is used as the sodium salt in hypercalcaemia of malignancy, and for the prevention of fracture and bone complications in Kenya patients with breast cancer and bone metastases. Ibandronate is also under investigation for the treatment and prevention of osteoporosis, with success rates being noted in most of the experiments.
Sodium ibandronate is administered by intravenous infusion, the dose being expressed in terms of ibandronic acid. Sodium ibandronate 1.13 mg is approximately equivalent to 1 mg of ibandronic acid. For hypercalcaemia of malignancy, a single dose of the equivalent of 2 to 4 mg ibandronic acid is given, up to a maximum of 6 mg; it is diluted in 500 mL of sodium chloride 0.9% or glucose 5%, and infused over 2 hours.
For the prevention of skeletal events in patients in Kenya with breast cancer and bone metastases, a single dose of the equivalent of 6 mg ibandronic acid is given, diluted as above, but infused over 1 hour. The dose is repeated every 3 to 4 weeks. Alternatively, ibandronic acid 50 mg daily may be given by mouth; specific instructions for its administration (see Precautions in Alendronate, should be followed to minimise adverse effects and permit adequate absorption.
Adverse Effects and Precautions
As for the bisphosphonates in general. Gastrointestinal symptoms such as abdominal pain, dyspepsia, and nausea are the most frequent adverse effects. Severe oesophageal reactions such as oesophagitis, and ulceration have occurred; patients should be advised to stop taking the tablets and seek medical attention if they develop symptoms such as new or worsening dysphagia, pain on swallowing, retrosternal pain, or heartburn. Gastric and duodenal ulceration have been reported. To minimise the risk of oesophageal reactions, precautions similar to those for alendronate should be observed. Hypocalcaemia should be corrected before starting ibandronate therapy. Transient fever after parenteral administration is common, and flu-like symptoms have been reported.
Malignant neoplasms of the bone.
Bisphosphonates are of benefit in some patients with metastatic bone disease not only to manage bone pain and hypercalcaemia, but to reduce skeletal complications such as fractures. Ibandronate is licensed for such use in many countries. Whether bisphosphonates can prevent the development of new skeletal metastases is unclear.
Treatment with bisphosphonates such as ibandronate may be considered in patients with moderate to severe symptomatic hypercalcaemia of malignancy in addition to rehydration and diuresis.
Martindale: The Complete Drug Reference: Ibandronic Acid
Like other bisphosphonates, ibandronate is poorly absorbed after oral administration; absolute bioavailability is less than 1%. Absorption is decreased by food, especially by products containing calcium or other polyvalent cations. Bioavailability is reduced by about 90% when given with food, by about 30% when given half an hour before food, and by about 75% when given 2 hours after food. About half of the absorbed portion is sequestered to bone; the remainder is excreted in urine. Plasma protein binding is about 87%. Bisphosphonates do not appear to be metabolised, and the unabsorbed fraction of ibandronate is excreted unchanged in the faeces.
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