A comparison of single and multiple intravenous infusions of 3-amino-1-hydroxypropylidene-1, 1-bisphosphonate (APD) in the treatment of hypercalcemia of malignancy.

Following rehydration with intravenous saline, 27 patients with hypercalcemia of malignancy were treated with a total of 32 courses of 3-amino-1-hydroxypropylidene-1, 1-bisphosphonate (APD) given by slow intravenous infusion. Twelve treatments consisted of daily infusions of APD for between two and six days whereas single-dose APD was used in 20 treatments. Mean albumin-adjusted serum calcium fell to the upper end of the reference range at seven days from the start of treatment, both in multiple-dose and in single-dose treatment groups. No relationship between total dose of APD and hypocalcemic response was observed. However, second treatments with APD following recurrence of hypercalcemia in five patients were significantly less effective than the original therapy, suggesting that resistance to APD may develop. Multiple-dose and single-dose intravenous APD treatments appear to be equally effective in the acute management of hypercalcemia of malignancy.