PAMIDRONATE DISODIUM IN THE TREATMENT AND MANAGEMENT OF HYPERCALCEMIA

Hypercalcaemia of malignancy is a common metabolic complication of adv anced malignancy, with or without associated metastatic bone involveme nt. The cause of the condition is uncontrolled osteolysis, induced by both local and humoral effects of tumour cells and dehydration and ina ppropriate renal tubular reabsorption of calcium. Treatment which inhi bits osteolysis relieves symptoms and improves quality of life. The tr eatment of choice is rehydration together with a single intravenous in fusion of a bisphosphonate. This restores normocalcaemia in 60-100% of cases, is well tolerated, and can be repeated as necessary. In compar ison with other treatments, including the bisphosphonates etidronate a nd clodronate, pamidronate produces rapid and sustained effects, with normocalcaemia being achieved within a few days of the initiation of t reatment, and a median duration of action of around 4 weeks following a single 90 mg infusion. Dose level may be adjusted according to initi al serum calcium levels, though there is current discussion both about the necessity for this and in regard to the optimal dose. Whilst ther e is some evidence that responsiveness to pamidronate relates to tumou r type, this has not been found in other studies using doses which are not too low. Pamidronate is the most effective of the currently avail able bisphosphonates, and is the drug of first choice in this indicati on.