Clinical experience with aminohydroxypropylidene bisphosphonate (APD) in the management of cancer-associated hypercalcaemia.

Fifty-five patients with symptoms caused by hypercalcaemia associated with cancer were treated with varying regimens of intravenously-administered aminohydroxypropylidene bisphosphonate after initial rehydration. Of 48 patients where adequate data were available, 32 (66 per cent) were rendered normocalcaemic and 16 (33 per cent) remained mildly hypercalcaemic. In these cases, failure to restore normocalcaemia was attributable to elevated renal tubular reabsorption of calcium in nine (18 per cent) and to inadequate suppression of bone resorption in seven (14 per cent). There was no significant difference in response and duration of effect (median 20 days) between single doses of 15, 25 and 45 mg, or when the 45 mg dose was administered over three, six or 24 h. These single dose regimens were similar in terms of effect on calcium levels and duration of action, to multiple daily doses of 15 mg for a mean of six days. While the effect of 5 mg dose was not significantly different from the higher doses, suppression of serum calcium levels was less marked and the effect on duration of action significantly shorter than with the 45 mg dose. In seven cases, treatment with a second course was less effective even with higher doses because suppression of bone resorption was poorer. These data indicate that there is little difference between the therapeutic effects of multiple 15 mg and single 15-45 mg intravenous infusions of aminohydroxypropylidene bisphosphonate in hypercalcaemia associated with cancer. A single intravenous infusion of a moderate dose (for example 15-30 mg) would be a convenient and effective way of treating most patients.