Jf. Flores et al., EVALUATION OF A 24-HOUR INFUSION OF ETIDRONATE DISODIUM FOR THE TREATMENT OF HYPERCALCEMIA OF MALIGNANCY, Cancer, 73(10), 1994, pp. 2527-2534
Background. Hypercalcemia is a serious and common complication of mali
gnancy. Etidronate, a known inhibitor of osteoclastic bone resorption,
is approved in the therapy of hypercalcemia of malignancy (HCM) at a
dose of 7.5 mg/kg/day infused during a period of 2-4 hours on 3 consec
utive days. A multicenter study was conducted to evaluate the safety a
nd efficacy of a single 24-hour infusion of etidronate disodium in pat
ients with HCM. Methods. Selected patients with HCM had disease refrac
tory to at least 24-hours of intravenous fluid (more than 3 1/day) wit
h two albumin-adjusted serum calcium concentrations greater than 11.5
mg/dl drawn 24 hours apart before etidronate treatment. Thirty patient
s were enrolled; 13 received 25 mg/kg for 24 hours, 12 received 30 mg/
kg for 24-hours, 3 received incorrect doses (2 overdoses, and 1 underd
ose) and 2 died of disease-related complications before day 7. Of the
25 evaluable patients, 15 were men and 10 were women. Median age was 5
3 years (range, 20-75 years). Twelve patients (6 in each treatment gro
up) had confirmed skeletal metastases. Results. During the week after
treatment, the 25 mg/ kg group had adjusted serum calcium levels fall
from a mean preinfusion baseline of 13.3 +/- 0.3 mg/dl (plus or minus
the standard error of the mean) to a mean nadir of 10.9 +/- 0.4 mg/dl
(the average of each patient's lowest calcium values). The 30 mg/kg gr
oup had adjusted serum calcium levels fall from a mean preinfusion bas
eline of 13.8 +/- 0.4 mg/dl to a mean nadir of 10.5 +/- 0.3 mg/dl. The
average day that nadir occurred was day 5.7 for the 25 mg/kg group an
d day 5.6 for the 30 mg/kg group. The mean maximum reduction (delta) d
erived from the patients' nadirs in the 25 mg/kg dose group was 2.5 +/
- 0.4 mg/dl and 3.3 +/- 0.3 mg/dl for the 30 mg/kg dose. Time to effec
t (either a partial response defined as a 15% or greater decrease in t
he adjusted serum calcium from the preinfusion value or a complete euc
alcemic response defined as a reduction to the laboratory's eucalcemic
range) occurred on average on day 4.6 in the 25 mg/kg group and day 3
.7 in the 30 mg/kg group. Nine of the 13 (69%) patients in the 25 mg/k
g treatment group had either partial or complete response to the 24-ho
ur infusion. Five of these patients (38% of the 13 patients) of the 25
mg/kg group had serum calcium levels fall to their laboratory's eucal
cemic range before day 7 (a complete response), 4 (31%) had partial re
sponse only, and 4 had no response. In the 30 mg/kg group, 11 of 12 (9
2%) patients had at least partial responses. Eight of the 12 (67%) pat
ients had adjusted serum calcium concentrations fall to the eucalcemic
range by day 7, 3 (25%) had a partial response, and 1 had no response
. Reported adverse experiences generally were attributable to the unde
rlying disease. The reduction in the serum calcium throughout the week
for the 30 mg/kg dose group was significantly greater than that for t
he 25 mg/kg group (analysis of variance, P < 0.0001). Conclusions. Eti
dronate, when administered intravenously at 30 mg/kg during a period o
f 24 hours, apparently was safe and effective in this study for treatm
ent of hypercalcemia in patients with a wide variety of tumor types. T
his regimen may offer a more convenient method of administration than
does standard etidronate therapy for the treatment of HCM.