The new bisphosphonate ibandronate in the treatment of tumor-induced hypercalcemia

Ibandronate is an aminobisphosphonate that specifically binds to bone miner al and inhibits the activity of osteoclasts. It is one of the most potent b isphosphonates that are currently being tested in clinical trials in patien ts with metabolic bone disorders and with osteoporosis. In animal models, i bandronate is twice, 10 times, 50 times, and 500 times more powerful than r isedronate, alendronate, pamidronate, and clodronate, respectively. We retr ospectively analyzed the clinical results of three studies with ibandronate in 340 patients and of two studies with pamidronate in 80 patients, leadin g to the registration of both agents for the treatment of malignant hyperca lcemia. Ibandronate can be used in patients with malignant hypercalcemia wi th and without metastases. A single infusion of 2 to 6 mg ibandronate effec tively reduces elevated serum calcium levels. The success of treatment depe nds on the baseline calcium level and the dose used. The time to normalizat ion of the serum calcium concentration varies between 2 and 7 days, with 4 days being usual in most patients. The median time to relapse (i.e., are-in crease in serum calcium) is 26 days and is similar for all doses. Treatment is more successful in patients with local osteolytic tumors (breast and he matologic tumors, response rates up to 100%) than in those with predominant ly humorally induced hypercalcemia in the other solid tumor types. Adverse reactions are minor, generally of no clinical relevance, and rarely require treatment. Local tolerability is excellent. Efficacy of ibandronate (Bondr onat(R)) is well comparable to that of other bisphosphonates, especially to those with an amino group like pamidronate. Ibandronate provides an effect ive and well-tolerated treatment for tumor-induced hypercalcemia.